2 - Chem21Labs

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CHEMISTRY II
Laboratory Manual
Dr. April French
Dr. Allison Soult
Dr. M. Meral Savas
Dr. François Botha
Dr. Carolyn Brock
Mr. Charles Griffith
Ms. Darla Hood
Dr. Robert Kiser
Dr. Penny O’Connor
Dr. William Plucknett
Dr. Donald Sands
Dr. Diane Vance
Dr. William Wagner
Department of Chemistry
University of Kentucky
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Copyright © 2013 by the Department of Chemistry, University of Kentucky
Copyright © 2013 by Hayden-McNeil, LLC on illustrations provided
Photos provided by Hayden-McNeil, LLC are owned or used under license
Copyright © 2013 by MeasureNet Technology, Ltd. for photos used in Chapter 4
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Table of Contents
Introduction to the Laboratory................................................................................ v
Chapter 1
Laboratory Safety...................................................................................................... 1
Chapter 2
Laboratory Notebooks and Reports........................................................................ 11
Chapter 3
Techniques for General Chemistry Lab.................................................................. 25
Chapter 4
Using MeasureNet and Probes................................................................................ 33
Experiment 10
Molecular Structures............................................................................................... 43
Experiment 11
Freezing Point Depression...................................................................................... 53
Experiment 12
The Decomposition of Hydrogen Peroxide............................................................ 57
Experiment 13
Chemical Equilibrium: Finding a Constant, Kc...................................................... 63
Experiment 14
Standardization and Titration................................................................................ 67
Experiment 15
Chemistry Is pHun!................................................................................................. 71
Experiment 16
Solubility of Calcium Hydroxide............................................................................ 77
Experiment 17
Analysis and Identification of Household Chemicals by Qualitative Analysis...... 81
Appendices
A Laboratory Equipment.............................................................................. 87
B Units and Constants................................................................................. 89
C Ions............................................................................................................ 93
D Solubility................................................................................................... 95
E Standard Deviation................................................................................... 97
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 General Chemistry II
 iv
Introduction to the Laboratory
Tell me and I forget. Teach me and I remember. Involve me and I learn.
—Benjamin Franklin
In the first semester of lab, you learned a variety of lab techniques, as well as how to
use basic glassware and equipment. As we continue in the lab, we will work more on
developing your lab skills. However, there will be a much greater emphasis on applying
what you have learned in lab by having students write the procedures needed to match
the purpose of the experiment. This course will also review and reinforce the concepts
you are learning or have learned in CHE 107. A laboratory course is different than a
lecture course because it allows you to be involved in what is happening. I hope that
you take full advantage of the opportunities available in this class to witness chemical principles in action, rather than seeing photos of, hearing someone talk about, or
reading about them.
This laboratory manual contains information about all the experiments we’ll be doing
as well as reference information about safety, lab reports, conversion factors, data on
various elements and compounds, and more. Additional information is also available
on the Blackboard website for this course (see the syllabus for information on accessing
the course website). You are strongly encouraged to read all the information in the lab
manual as well as the information posted on the website. Reviewing this information
is critical to your success in the course. One of the most important thing you can do
in this course is READ.
You cannot escape the responsibility of tomorrow by evading it today.
—Abraham Lincoln
There are many components to your grade for this course, which are outlined in the
course syllabus. You are responsible for reading the syllabus and adhering to all assignment due dates and policies. You should read the syllabus carefully and direct any
questions you have to your Teaching Assistant and/or to the Lab Supervisor. It is in your
best interest to read the syllabus and get any questions answered sooner, rather than
later, so that you are not penalized for missing a due date or for misunderstanding a
course policy (i.e., mandatory attendance).
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 General Chemistry II
It is important that you take an active role in your learning by seeking help, asking questions, and participating
in this course. Think about taking a class like a trip
to the grocery store. You don’t go to the grocery and
expect someone to know exactly what you need and
bring it to you. You have to figure out what you need
and go looking for it. Maybe it’s a store you’ve never
been in before and you have to walk around a little to
find where the cereal aisle is or the frozen foods are. As
you walk through the store, you may be offered help
by clerks, but you’re sure you can do it alone. Then
when the clerks disappear, you realize you do need help!
Maybe you’ve found the cereal aisle, but you can’t find
the Super Sugar Rings that you absolutely must have in
order to function. Now, you’re faced with some choices:
There are many people involved in this course who each
have their own important role.
1. Keep looking in the same place you’ve been looking because you’re positive you can do this on your
own, after all if you’re able to get to the grocery
store, then you should be able to find the Super
Sugar Rings.
Teaching Assistant: TAs are responsible for the direct
supervision of students in the laboratory, presentation
of material in the lecture, helping students, grading lab
reports, and giving input on students’ course grades.
2. Give up because if you can’t find them, they must
not be there and you’ll have to do without.
3. Go find someone who can help you and ask them
where the Super Sugar Rings are and find out that
because the Super Sugar Rings are on sale this week,
they are on the end cap of the soda aisle instead of
being in the cereal aisle.
The same thing applies in this course, there are people
to help you along the way but you have to find them
and bring your questions to them so they know exactly
what you need and can help you.
Electronic Resources
There is additional information on experiments through
Blackboard including tutorials, videos (i.e., Using a
Burette, Dispensing Liquids and Solids), and sample
calculations. Some of the information will be required
viewing, while other resources are there to help you
when you need it.
 vi
Lab Supervisor: The job of the lab supervisor is to
supervise the teaching assistants, write quizzes and exams, help students, resolve student-TA problems, assign
final course grades, and other administrative tasks. The
lab supervisor has regularly scheduled office hours, but
is generally available at other times.
Storekeeper: A member of the chemistry stockroom
staff works with the General Chemistry laboratory
courses by preparing chemical and unknown solutions,
setting up necessary supplies and reagents, and helping
students replace missing and/or broken equipment.
Student: Your job is to come to class prepared to do
the assigned experiment in the allotted time, work with
other students on experiments, follow safety rules, keep
lab spaces clean, submit all assignments on time, and to
READ. You should read the syllabus, the lab manual,
the website, and any other material that is given to you
so that you know exactly what to expect in this course.
The Director of General Chemistry oversees the administration of this course and can discuss problems
or concerns that a student does not feel is resolved by
discussing it with their TA and/or the Lab Supervisor.
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Laboratory Safety
By its nature the chemical laboratory can be a dangerous place to work. The improper
use of chemicals and equipment can cause severe and/or permanent damage to your
body. And you are not the only one at risk. Your actions can affect your coworkers,
those who follow, and the environment. One of the more important aspects of your
chemistry lab experience will be learning how to perform experiments as safely as is
humanly possible. You will learn how to protect yourself and others from the hazardous
conditions created by your experimentation.
1-1 Safe Laboratory Practices
It is common knowledge that doing chemistry is a hazardous activity. But so is driving a
car or cooking. As with these other activities, the trick to safely working in a chemistry
lab is to learn safe practices and develop safe working habits. This course is designed
to teach safe lab practices and to help you develop habits that will lead to efficient, effective, and safe experimentation.
When performed correctly, the experiments presented in this course are safe. But this is
a teaching lab. Mistakes will be made. Misinterpretation of the instructions or use of the
wrong chemicals can result in a serious accident. And no matter how careful you are,
the student working next to you may be doing something to endanger your health that
you are helpless to prevent. No matter how much faith you have in your ability to work
safely in the laboratory it is foolish to believe that an accident can’t happen to you.
The safety rules for working in this lab are designed with this idea in mind. If you faithfully adhere to these rules, and to your instructor’s precautions, you will find working
in the chemical laboratory to be no more dangerous than working in a kitchen or
driving a car.
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1 • Laboratory Safety
Keep in mind that safety rules don’t exist just to protect
you and your lab mates. They are also intended to help
instill safe working habits. Because habits are developed
by repetition, it is expected that you will adhere to these
rules at all times, regardless of the level of danger posed
by any particular experiment.
Chapter
1
1-2 Safety Issues
Eye Protection
Your eyes are quite possibly the most fragile parts of
your body. They are certainly very important and impossible to replace. And they face many dangers in a
chemical lab. Proper protection of the eyes is mandatory
in a chemical lab.
While explosions pose the most dramatic danger to
your eyes, they are not very common in chemistry
labs. The greatest danger is from splashed chemicals
and fumes. Safety glasses provide protection against
explosions, but are not effective against splashes and
fumes. Goggles with perforations are better, but still not
adequate to handle most chemical fumes. Only vented
goggles or full safety shields are considered adequate
to protect you from splashed chemicals, flying glass,
and noxious fumes.
Figure 1.1. Vented goggles.
Chemistry labs are equipped with eyewash stations
to provide first aid in the event some foreign body or
chemical enters the eye. You need to know the location
and proper operation of the nearest eyewash to your
work space. Should you get a chemical in your eye,
or should chemical vapors cause your eyes to water,
immediately wash your eyes with lots of water. To be
effective, eye washing must be continuous for at least
15 minutes.
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Figure 1.2. Eyewash fountain.
There is no consensus on the danger related to wearing contact lenses in the lab. To date, there is no data
that shows either greater or lesser risk from wearing
contacts. On the one hand, fumes that get in the eye
will probably get under the lens. In this event the lens
will aggravate any exposure. On the other hand, the
contact will protect the cornea from direct chemical or
physical contact.
Clothing
You should think about what you will wear to lab. Many
fabrics, such as nylon and polyester, react with common lab chemicals and burn well. Cotton clothing is
the best. To protect yourself against splashed or spilled
chemicals you should also cover as much of your skin
as is practical. That means a long sleeve shirt and long
pants. Finally, as a first line of defense, a lab coat or
apron can’t be beat.
Don’t forget to consider what shoes to wear. Because
broken glass and spilled chemicals are common to the
lab, closed-toed, non-absorbent shoes are a must. Consider what would happen if you were wearing canvas
sneakers and socks and spilled an acid on your shoe. It
would soak through the shoe and through the sock to
your foot. In the time it would take you to get the shoe
and sock off significant damage would be done.
Chemistry labs are equipped with safety showers to
provide first aid should you spill any chemical on your
C h a p t e r
1 • Laboratory Safety 
Chapter
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Figure 1.3. Lab coat and apron.
Figure 1.4. A lab safety station.
skin or clothing. You need to know the location and
proper operation of the safety showers in your lab. Immediately wash the affected area with lots of water and
continue the washing for 15 minutes.
to use gloves must balance the added protection they
provide for the hands against the loss in dexterity.
A note on chemical contact.
There are two dangers
from chemical contact with skin:
1. destruction of tissue (chemical burns) and
Chemical burns can be just as nasty as heat burns
2. poisoning due to absorption through the skin.
and often cause no pain until after damage is done.
When you will be working with a sufficiently dangerous
Any chemical contact with skin should be treated as a
chemical, you will be instructed to wear gloves.
potential chemical burn. When this happens, contact
your instructor.
Gloves
Hands present a special case. When we manipulate glassware and other laboratory equipment, we depend on
our sense of touch to direct our activities. Gloves limit
our sense of touch and, therefore, our dexterity. Using
gloves increases the chance of an accident. In addition,
the skin on hands is tougher than other skin. It comes
with its own protective layer of callouses. The decision
Reagents
The place where reagents are stored is known as the
reagent bench. It will have most of the non-dangerous chemicals and other supplies that you will need to
perform your experiments. More dangerous chemicals
are stored in a hood. The proper procedure for obtaining a reagent is to take an appropriate container to the
bench and take only what you need. Transporting a
large container of any chemical can be hazardous and
is to be avoided.
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 C h a p t e r
1 • Laboratory Safety
Precautions
Prior to each experiment your instructor will tell you
how to properly use chemicals and equipment. You are
expected to follow these instructions.
Chapter
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Waste Disposal
You will need to become familiar with the various kinds
of waste generated in a chemistry lab and the proper
protocol for disposing of each. The kinds of waste are:
•
Solid chemical waste.
•
Glass waste.
•
Garbage (stuff that can go in the garbage can: no
glass, no chemicals).
•
Liquid organic waste.
•
Acidic water solutions.
•
Basic water solutions.
•
Heavy metal water solutions.
•
Drain water. (Only neutral water solutions that do
not contain heavy metals or organics can be poured
down the drain. No solids!)
Figure 1.5. A reagent bench.
When using reagent bottles you must be observant
for spills. One common cause of chemical burns in a
teaching lab is reagent on the outside of the bottle. It
is easy to slop reagent down the outside of the bottle.
If you do so, make sure you clean it up. And watch for
wet bottles!
When using reagent bottles you must also avoid contamination. You must develop habits that will minimize
the possibility of contamination.
•
NEVER set the cap to the reagent bottle down.
Hold it between the second and third fingers of
one hand.
•
NEVER insert objects (including pipets) into reagent
bottles. Instead, transfer some of the reagent to a
clean beaker and pipet from this container.
•
NEVER return unused reagent to the reagent bottle.
Dispose of all unused reagent as chemical waste.
Labels
Check the label carefully before you use a reagent. Use
of the wrong reagent will ruin your experiment and
could result in a serious accident. You also need to make
sure you label everything you make and use in the lab.
Many accidents result from assumptions made about
unlabeled containers.
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Figure 1.6. Chemical waste hood.
C h a p t e r
Clean Up
At the end of the class you are expected to turn off all
water and gas jets, return all borrowed items, and put
all of your equipment back into your locker and lock it.
You also must leave a clean work bench for the student
that follows.
Accidents
Should an accident occur, it is important to notify
the instructor immediately. Even something as
seemingly innocuous as cutting yourself on a broken
piece of glass could become very nasty if that glass were
contaminated with a dangerous chemical. Let your instructor help to judge the severity of any incident.
Evaluation
The most basic objective of a chemistry lab course is to
teach you how to safely work in a chemical lab. Your
grade will depend, in part, on how well you demonstrate your knowledge of safe laboratory practices. You
should expect to see the material presented here on the
exams you take. In addition, your instructor’s evaluation of your lab performance will be based, in part, on
your adherence to safe laboratory practices and the lab
rules. Finally, should you demonstrate a lack of regard
for safety rules, or laboratory safety in general, you will
be prohibited from working in the lab.
1 • Laboratory Safety 
1-3 Safety Assignment
1. When are safety goggles to be worn in the lab? Who
must wear them?
Chapter
2. What function do the hoods serve? When must
you use them?
1
3. Why must shoes be worn in the lab? Why are sandals prohibited?
4. Your neighbor is carrying a bottle of concentrated
nitric acid back to the lab bench. He trips and drops
the bottle which breaks and splatters its contents
all over your legs. What do you do? What did your
neighbor do wrong?
5. Make a diagram of your lab room. On this diagram
indicate the location of the following items:
a. your workspace
b. the hoods
c. the nearest safety shower
d. the nearest eyewash station
e. the nearest fire extinguisher
f. the first-aid box
g. the exits
h. the reagent bench
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 C h a p t e r
Chapter
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1 • Laboratory Safety
C h a p t e r
Safety in a Chemistry Laboratory
One of the most important aspects of any chemistry lab
is safety and this course is no exception. All students
are required to read the safety information in the lab
manual, watch a safety video, sign and submit a copy of
this form, and pass a safety quiz in order to participate
in this course. While some of this may seem repetitious,
it illustrates the importance we place on your safety and
the safety of those around you. Violation of any safety
rules will not be tolerated. Failure to remedy an unsafe
situation will result in students being asked to leave the
laboratory. Missing an experiment due to a student’s
failure to follow safety rules will not be considered an
excused absence. Students should read and understand
the rules listed below.
1. Your eyes are the most vulnerable part of your body
to the dangers of working in a chemistry lab. You
are required to wear protective eyewear whenever
you or anyone else in the lab is transporting or
using chemicals and/or glassware. Only chemical
splash goggles which meet the current safety standards are permitted. The cost of goggles is included
in the cost of Chem21. When you have paid for
Chem21 and submitted your access code online,
you will receive your goggles from your TA during
Experiment 10. You will be required to bring and
wear your goggles to participate in lab. Sunglasses
and prescription glasses are not acceptable forms
of eye protection. Other types of goggles must be
approved by the Laboratory Supervisor.
2. Appropriate clothing must be worn, including long
pants or skirts, shoes with closed toes (shoes which
cover your feet completely are preferable), and
shirts which meet the top of your pants or skirt (i.e.,
no bare stomachs or backs). Students not wearing
appropriate clothing will be asked to leave the lab
immediately.
3. No smoking, drinking, or eating (including gum)
at any time in the laboratory. All bottles, cups, and
food must be left outside the lab or placed into your
closed backpack, bag, or pocket. Food or beverage
containers must be disposed of prior to entering the
lab and cannot go into the trash cans in the lab.
1 • Laboratory Safety 
4. Never work alone in the laboratory. Students must
be supervised by a TA or the Lab Supervisor during
all experiments.
Chapter
5. Never leave an experiment or running equipment
unattended. Surprises are usually not a good thing
in a chemistry lab.
1
6. Only do the assigned experiment. Additional experiments are not allowed to ensure the safety of
you and those around you.
7. Do not remove chemicals, equipment, or glassware
from the laboratory. Any student alleged to have
removed any of the items listed above from the
laboratory will be reported to the police. Any student caught removing any of the items listed above
will be prosecuted. If a student is convicted, the case
will be turned over to the Dean of Students and the
Department of Chemistry may recommend that the
Dean of Students seek the harshest of University
sanctions, which includes expulsion.
8. Do not wear gloves out of the laboratory, regardless
of whether you have started working in the lab or
not.
9. Know the location of all safety equipment in the
room as well as the location of the nearest exit from
the room and building.
10. If there is an accident, no matter how minor, contact your TA immediately.
11. Double-check all labels before using them in an
experiment to make sure it is the correct chemical
and concentration. Substituting another chemical or concentration could cause unexpected and
dangerous consequences.
12. Discard broken, cracked, or chipped glassware
immediately in the appropriate containers. Do
not place glassware in the trash cans under any
circumstances. Broken items can be replaced by
contacting the stockroom.
7
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 C h a p t e r
Chapter
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1 • Laboratory Safety
13. Tilt test tubes while heating, being careful not to
point them at anyone.
16. Dispose of waste in the appropriate container(s).
When in doubt, ASK!
14. Wipe down your workspace with a wet towel before leaving the laboratory to ensure that other
students are not unknowingly placed in contact
with chemicals.
17. If the fire alarm goes off, turn off your equipment,
collect your belongings, and proceed to the nearest
exit. All labs are to meet their TA on the hill where
the TA will take attendance. The Lab Supervisor will
make all decisions regarding the completion of the
lab on a case-by-case basis.
15. If you have any medical condition (allergies, pregnancy, etc.) which may affect your performance in
the lab, please notify the Lab Supervisor immediately so that any safety issues can be addressed.
By signing below, I indicate that I have read and understand the safety information provided to me in the lab
manual, on the safety video, and by my TA. I also realize that it is my responsibility to follow all safety rules
and that I will be removed from the laboratory for repeated violations of these rules.
Initial by each of the following statements to indicate that you have read them.
•
I understand the policies of this course as outlined in the syllabus.
•
I have seen the list of due dates for all assignments in the syllabus.
Name (print) ________________________________________________________________________________________
Signature ___________________________________________________________________________________________
Date
8
Section
TA
C h a p t e r
One of the most important aspects of any chemistry lab
is safety and this course is no exception. All students
are required to read the safety information in the lab
manual, watch a safety video, sign and submit a copy of
this form, and pass a safety quiz in order to participate
in this course. While some of this may seem repetitious,
it illustrates the importance we place on your safety and
the safety of those around you. Violation of any safety
rules will not be tolerated. Failure to remedy an unsafe
situation will result in students being asked to leave the
laboratory. Missing an experiment due to a student’s
failure to follow safety rules will not be considered an
excused absence. Students should read and understand
the rules listed below.
1. Your eyes are the most vulnerable part of your body
to the dangers of working in a chemistry lab. You
are required to wear protective eyewear whenever
you or anyone else in the lab is transporting or
using chemicals and/or glassware. Only chemical
splash goggles which meet the current safety standards are permitted. The cost of goggles is included
in the cost of Chem21. When you have paid for
Chem21 and submitted your access code online,
you will receive your goggles from your TA during
Experiment 10. You will be required to bring and
wear your goggles to participate in lab. Sunglasses
and prescription glasses are not acceptable forms
of eye protection. Other types of goggles must be
approved by the Laboratory Supervisor.
2. Appropriate clothing must be worn, including long
pants or skirts, shoes with closed toes (shoes which
cover your feet completely are preferable), and
shirts which meet the top of your pants or skirt (i.e.,
no bare stomachs or backs). Students not wearing
appropriate clothing will be asked to leave the lab
immediately.
3. No smoking, drinking, or eating (including gum)
at any time in the laboratory. All bottles, cups, and
food must be left outside the lab or placed into your
closed backpack, bag, or pocket. Food or beverage
containers must be disposed of prior to entering the
lab and cannot go into the trash cans in the lab.
1 • Laboratory Safety 
4. Never work alone in the laboratory. Students must
be supervised by a TA or the Lab Supervisor during
all experiments.
Chapter
5. Never leave an experiment or running equipment
unattended. Surprises are usually not a good thing
in a chemistry lab.
1
6. Only do the assigned experiment. Additional experiments are not allowed to ensure the safety of
you and those around you.
7. Do not remove chemicals, equipment, or glassware
from the laboratory. Any student alleged to have
removed any of the items listed above from the
laboratory will be reported to the police. Any student caught removing any of the items listed above
will be prosecuted. If a student is convicted, the case
will be turned over to the Dean of Students and the
Department of Chemistry may recommend that the
Dean of Students seek the harshest of University
sanctions, which includes expulsion.
8. Do not wear gloves out of the laboratory, regardless
of whether you have started working in the lab or
not.
9. Know the location of all safety equipment in the
room as well as the location of the nearest exit from
the room and building.
10. If there is an accident, no matter how minor, contact your TA immediately.
11. Double-check all labels before using them in an
experiment to make sure it is the correct chemical
and concentration. Substituting another chemical or concentration could cause unexpected and
dangerous consequences.
12. Discard broken, cracked, or chipped glassware
immediately in the appropriate containers. Do
not place glassware in the trash cans under any
circumstances. Broken items can be replaced by
contacting the stockroom.
9
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 C h a p t e r
Chapter
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1 • Laboratory Safety
13. Tilt test tubes while heating, being careful not to
point them at anyone.
16. Dispose of waste in the appropriate container(s).
When in doubt, ASK!
14. Wipe down your workspace with a wet towel before leaving the laboratory to ensure that other
students are not unknowingly placed in contact
with chemicals.
17. If the fire alarm goes off, turn off your equipment,
collect your belongings, and proceed to the nearest
exit. All labs are to meet their TA on the hill where
the TA will take attendance. The Lab Supervisor will
make all decisions regarding the completion of the
lab on a case-by-case basis.
15. If you have any medical condition (allergies, pregnancy, etc.) which may affect your performance in
the lab, please notify the Lab Supervisor immediately so that any safety issues can be addressed.
By signing below, I indicate that I have read and understand the safety information provided to me in the lab
manual, on the safety video, and by my TA. I also realize that it is my responsibility to follow all safety rules
and that I will be removed from the laboratory for repeated violations of these rules.
Initial by each of the following statements to indicate that you have read them.
•
I understand the policies of this course as outlined in the syllabus.
•
I have seen the list of due dates for all assignments in the syllabus.
Please keep this copy of this form for your reference. Questions on safety may appear on any exam or quiz
in this course.
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Laboratory Notebooks and Reports
During an experiment, students collect data and make observations about an experiment.
This information should be recorded in your lab notebook and then used to complete
the assignment(s) in the schedule. The lab notebook is used as an original record of your
data, while a lab report is the formal presentation and discussion of the experiment and
your results. The lab report should be typed and contain no errors, but the lab notebook
will be handwritten and may contain errors.
Laboratory Notebooks
Why are lab notebooks so important? A lab notebook is the original record of your
data and should contain any information that you might need when writing your lab
report. If there is something you are not sure you will need, write it down anyway. If
you have it and don’t need it, it’s not a problem. If you need it and don’t have it, you
have a problem.
If you plan a career that involves research, a lab notebook is very important. U.S. Patents
are decided by the date of invention, not the date of application. Failing to accurately
document and date your findings means that the patent application could be denied
which could result in the loss of substantial amounts of fame and fortune for you
and/or your employer. If you are planning a career in a medical field, it is imperative
that you accurately record all patient information. Failure to document symptoms and
test results could result in a misdiagnosis which could lead to being sued for medical
malpractice.
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 C h a p t e r
2 • Laboratory Notebooks and Reports
Before Lab
Chapter
2
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C h a p t e r
2 • Laboratory Notebooks and Reports 
After Lab
Chapter
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 C h a p t e r
2 • Laboratory Notebooks and Reports
 Do not write the information on a separate
The lab notebook (purchased separately) should be used
to record the following information:
•
Chapter
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Basic information
Name
 Experiment number and name
 Date (all pages should be used in sequential
order)
 Name of lab partner
 Course and section number
 Signature of student
 Signature of TA
•
Procedure planned and carried out in lab. Do not
print out the lab manual for lab.
•
List of any changes to the procedure published in
the lab manual.
 This should include changes announced in
class, on Blackboard, etc.
piece of paper and transfer it.
 It is okay if the lab notebook is not perfect or
contains errors.
 Do not record data in the middle of the procedure.
•
Never remove pages from your lab notebook. The
pages are numbered sequentially and should remain
intact even if you use additional pages for calculations or other notes.
•
Mark out any errors with a single line so that the
original information is still legible but the line
clearly indicates that it is incorrect.
•
Organize data in tables when collecting multiple
values.
•
Label all values (i.e., volume of water used).
Do not have “orphaned” numbers. All values
should have labels and units.

•
Qualitative data (i.e., after addition of HCl, a lemon
yellow precipitate formed).
•
Quantitative data (i.e., mass of the metal cube—
2.5434 g, 2.3425 g, 2.4344 g).
 Note the description of the item as well as the
units.
•
•
File names of any data collected and saved electronically.
 Include some type of identifying information
for all electronic data files such as the initial
or final temperature, approximate equivalence
point, etc.
All calculations, making sure to show all steps. If
you make an error, you, a TA, or Lab Supervisor can
use this information to find the error.
When writing information in your lab notebook, you
should always do the following:
 14
•
Always write in blue or black ink.
•
Always write your data directly in your lab notebook.
•
Include units for all numbers.
•
Record all qualitative observations.
•
Record all unknown numbers/letters.
•
Record concentrations of all solutions used.
At the end of each lab session, have your TA sign your
lab notebook and then turn in the copy of your results
to them. This allows your TA to verify data presented in
your report and identify any recurring problems in the
experiment. The data in your report should match that
in your lab notebook exactly. Any discrepancies should
be explained prior to submitting the report.
Assignments1
Part of your grade in this course will be based upon the
assignments submitted for each experiment. There are
three main types of assignments which you will complete in this course:
1
Some information and descriptions of categories for the grade
sheet come from http://labwrite.ncsu.edu, a project funded
by the National Science Foundation and available to students
everywhere.
C h a p t e r
•
Chem21: Online data analysis which will be completed for each experiment.
• Lab Report: Students will complete either a section
or a full report for most experiments. See the course
schedule for a description of what is due. All final
versions of reports or portions of them are to be
submitted electronically on Blackboard.
• Peer Review: Your TA and two of your classmates
will use a feedback form to help you improve your
lab report before you submit the final copy on
Blackboard.
• Worksheet: A longer assignment on Chem21 labs,
generally completed on weeks you don’t submit
a lab report, is worth more points than normal
Chem21 assignments.
See the syllabus for an explanation of how each assignment contributes to your final course grade.
Laboratory Reports1
The purpose of a lab report is to explain the theory
behind the experiment, present the results, and discuss
how the results relate to the theory. Someone who has
not done the experiment or even read the experiment
in the lab manual should be able to read your lab report
and understand what you were trying to do, see the
summary of your data, and understand the results of
your experiment. Lab reports allow you the opportunity to interpret your data and relate it (or not) to the
theory behind the experiment. While it is much easier to
explain data that agrees with the theory, you will probably find that in one or more experiments, you might
get an unexpected result. Do not change your data
or use someone else’s data just because your numbers
“look bad.” What is more important is that you either
see potential sources of error that could have led to the
results and/or that you try to explain the results that
disagree with the underlying theory.
We understand that some students have never written
a lab report before or have written reports following a
different format. If you are in this situation, you are
not alone. All students should follow the guidelines
presented here to write their reports and contact their
TA for help, if needed.
2 • Laboratory Notebooks and Reports 
Do NOT copy another student’s work when
writing your lab report. Do not use someone
else’s report as a “guide” or a “template.”
Students may discuss content but lab reports
(including text, tables, equations, graphs,
etc.) should be written independently of other
students and their lab reports.
Chapter
2
Lab reports are submitted electronically and copies of
all reports for both the current and previous semesters
are kept on file. Reports submitted electronically are
compared to all reports submitted in both previous
and current semesters. If you copy from another
student, you will get caught. Using someone else’s
work without giving them the appropriate credit is
plagiarism, which is an academic offense. Academic
offenses are taken very seriously by the Department of
Chemistry and the University of Kentucky.
Penalties for academic offenses can be as severe as suspension, dismissal, or expulsion from the University.
The minimum penalty in general chemistry lab courses
is a zero on the assignment and a reduction of the final
course grade by one letter grade. If you have questions
about academic offenses or plagiarism, please contact
your TA or the lab supervisor; review the relevant rules
of the University Senate (Rule 6.3); or contact the Writing Center.
Each part of the lab report will be discussed in more
detail, but the following are some general tips on writing lab reports:
•
•
Reports must be completely typed.
Save early, save often.
Computers lock up and break down. Save your
work and back up your files.

•
Microsoft Word is preferred when writing your
reports.
 As the lab manual went to press, Microsoft
Office is available free to students at http://
download.uky.edu. Help with the download
and/or installation is available from the IT
Customer Service Center in McVey Hall.
15

 C h a p t e r
2 • Laboratory Notebooks and Reports
 Microsoft Office is installed on all campus


Chapter
2


computers.
Students should not use Microsoft Works as
it does not handle images well and frequently
creates files larger than 10 MB which will not
be accepted on Blackboard.
Mac users should see the FAQ for additional
information.
Microsoft Word is also available in campus
computer labs.
If Word is not an option to write your report,
you may use OpenOffice (www.openoffice.
org) but you must save the file as the type
“Microsoft Word 97/2000/XP.”
•
Reports must be submitted electronically using the
link given in the course syllabus and on Blackboard.
Paper or e-mailed copies will not be accepted.
•
Proofread your lab report before submitting it to
check for grammatical or spelling errors.
•
Do not wait until the last minute to complete your
report. If you need help late at night or in the early
hours of the morning before the report is due, you
may not be able to get it before the report is due.
 It is always a good idea to make sure you can
open any data files shortly after your lab session
in case there are any problems with the file.
•
Your lab report will be graded by your TA who may
have their own formatting preferences (spacing,
font, graph size, etc.).
•
Always separate parts of your lab reports with headings for each section (i.e., Results, Discussion, etc.).
•
With the exception of the conclusion, the rest of
the report should be written in third person.
 Instead of saying “I recorded the mass of the
sample,” say “The mass of the sample was
recorded.”
Lab reports will be graded electronically and an Excel
spreadsheet will be returned to you with your grade.
An example of the spreadsheet is included on page 17.
 16
This also serves as an outline for explaining the different parts of a lab report. You should receive your grade
within one week of the due date of the report. If you
are not receiving your grades in a timely manner, please contact the Lab Supervisor.
The point value for each item will vary with each experiment depending on the level of difficulty for a particular
section. The values in the sample grade sheet are meant
as an example. Each item is graded on a scale of 1 (excellent) to 0 (poor) in 0.25 point increments. This value
is then multiplied by the point value to get your score
for that particular section of the report. Your TA should
include comments in the grade worksheet returned to
you and/or in a general e-mail to all students. If you
have questions about the grade on your lab report, you
should see your TA first since they are the ones that
graded the report. If you still have questions, contact
the Lab Supervisor.
Contact your TA as soon as you have questions so that
you can make the needed corrections on future lab reports. It is in your best interest to talk to your TA about
your grades as questions arise. Waiting until all assignments have been submitted is not helpful for you.
The format for lab reports varies among different fields
of science (i.e., physics, biology, chemistry) and there
can be differences within one field. While the components of each may be generally the same, they may use
different section titles, expect different things, or have
different standards. Likewise, any lab reports you wrote
in high school may be very different than what you will
do in this class. The following information discusses
what to do and not do for each section of your lab report. Please note that the items listed follow the grading
sheet which will be used to grade your report.
Title
File named correctly and in the correct format
• Follow the format experimentnumber_lastname_
firstname.doc
•
Jane Doe submitting the report for Experiment #8
would name the file 8_doe_jane.doc
•
The file must be in MS Word 2003 or later format.
2 • Laboratory Notebooks and Reports C h a p t e r

Student Name: Jane Doe Experiment #: 7 Section
Points
0, 0.25, 0.50, 0.75, 1.0
Poor to Excellent
Miscellaneous
Deductions for late reports, safety, etc. (use minus sign) or points for rough draft
(#2 & #11 only)
Title (3)
File named correctly and in correct format
Header information
Describes lab content concisely, adequately, appropriately
1
1.00
0.75
0.75
1
1.00
1
2.00
Chapter
2
Introduction (6)
Successfully establishes the scientific concept of the lab
Effectively presents the objectives and purpose of the lab
Includes support or reasoning for objectives, including equations and formulas
0.75
1.50
1
2.00
1
1.00
Methods (1)
Includes appropriate reference or enough details to replicate unpublished procedure
Discussion (14)
Statement of purpose/hypothesis
Opens with summary of relevant results
Explains if results support original purpose/hypothesis
1
2.00
0.75
2.25
1
3.00
Explains why the results support the original purpose/hypothesis or not
0.75
2.25
Addresses other issues important to the lab and their effect on the results
0.5
1.50
Convincingly describes what has been learned in the lab
1
1.00
Has successfully learned what the lab is designed to teach
1
1.00
0.75
0.75
Conclusion (2)
Presentation (4)
Citations and references adhere to proper format
Formatting of report is correct
Report is written in scientific style: clear and to the point
Grammar and spelling are correct
1
1.00
0.5
0.50
0.75
Points Earned
Total Possible Points
0.75
23.25
30
TA: Joe Smith Date: 10/15/2009 7_Jane Doe
17

 C h a p t e r
2 • Laboratory Notebooks and Reports
Header information
Above the title, you should give some basic information
including the following:
•Name
• Course and section number
• TA’s name
• Lab partner’s name
•Date
Chapter
2
Describes lab content concisely, adequately,
and appropriately
The title should give the reader an idea of what the
report is about. A good title should:
•
Be descriptive and concise.
•
Be appropriate to the experiment.
•
Not be too long (usually no more than one line)
and not a complete sentence.
•
Not be identical to the lab manual.
Introduction
The purpose of the introduction is to give some background and theoretical information for the experiment
in order to explain what concepts or theories are applicable to the experiment, explain what you are trying to
determine in the experiment, and why this experiment
should support the theoretical concepts stated.
Successfully establishes the scientific concept of the lab
• Gives all relevant theoretical and background information for the experiment.
•
Explains the concepts in a logical manner.
•
Discusses general concepts of experiment.
•
Using the lab manual or other sources as a reference is acceptable, but the use of direct quotations
should be minimal.
Effectively presents the purpose/hypothesis and objectives
for the lab
• The purpose/hypothesis should be specific and
pertinent to the experiment.
 18
•
The purpose/hypothesis should in some way predict
the outcome of the experiment based on theoretical information, not on the data collected for the
experiment.
•
Objectives should be stated in your own words.
Includes support or reasoning for objectives including all
needed chemical equations and formulas and mathematical formulas
• Explain how the experiment will support the purpose/hypothesis.
•
Gives information specific to this experiment.
•
Include any relevant chemical equations and/or
formulas. Use Equation Editor for any mathematical
formulas.2
•
Include any relevant mathematical formulas, defining any variables, and an explanation of when the
formula can be used (i.e., discuss any limitations
of formula).
Methods
The methods section should outline the exact experimental procedures followed. If the procedure is
published in the lab manual, you should not rewrite
the procedure, but instead reference it and make note
of any changes.
When procedure is in lab manual
• Include all necessary information for the source of
the procedure including page numbers and whether
there are changes or not.
•
Changes, including changes in equipment or materials, are to be clearly explained.
•
If there are no changes to the procedure in the
lab manual, you should state “No changes to the
published procedure.”
2
Equation Editor is available in MS Word and OpenOffice. For
help in finding, installing and/or using Equation Editor on your
computer, see the information posted on Blackboard or search
for more information on the Web using a search engine, such as
www.google.com.
C h a p t e r
•Do not rewrite or quote the complete procedure
from the lab manual.
•Do not include any results or data in the procedure.
When procedure is not in lab manual
• Write procedure clearly so that it can be replicated
using only what is written.
•
Include a list of needed chemicals, equipment, and/
or materials.
•
Include all steps that you planned to do and
steps that were added when you actually did the
experiment.
•
As a rule of thumb, give enough detail so that your
mom could repeat the experiment.
•Do not include how to calculate values or that you
need to do a calculation.
•
Cite any source used when developing your
procedure.
Results
The results section of a report generally includes your
data as well as any calculations and/or graphs. Rather
than writing a results section in your report, you will
complete this online at www.chem21labs.com. You
will receive an e-mail with your login information after
the last day to add a class.You will need to purchase access either by buying an access code at the bookstore
or directly through the Web site. Access is good for one
semester. You will need this code when you log in to
Chem21 to have access for the semester.
Do not change your purpose/hypothesis because it
does not match your results.
Chapter
2
Place this at the very beginning of the discussion
section.
Summary of relevant results
• Include this information immediately after your
restatement of purpose/hypothesis.
•
Gives summary of key results including, but not
limited to, average values, percent error, and/or
standard deviation.
•
Make sure all numerical values have the correct
units and are correctly formatted (i.e., for standard
deviation: 36.1 ± 1.1 g).
•
Do not repeat all of the data reported in the results
section.
Explains if results support original purpose/hypothesis of
experiment
• State whether or not experimental results support
purpose/hypothesis.
Explains why the results support or don’t support the original purpose/hypothesis
• Compare the experimental results to the theoretical
predictions.
•
Discussion
The discussion section is where we bring the theoretical information (from the Introduction) and the
experimental information (from the Results) together.
The discussion is also where potential sources of error
should be discussed. The order of information
in the discussion is important. In general, the
discussion should be longer than the introduction. If
not, the introduction is too long and/or the discussion
is too short.

Statement of purpose/hypothesis
• One or two sentences restating the original purpose/hypothesis of the experiment based on the
theoretical and background information.
•
•
2 • Laboratory Notebooks and Reports Explain why the results support or don’t support
the purpose/hypothesis.
Addresses other issues pertinent to the lab and their effect
on the results
• Discuss at least three potential sources of error.
Potential sources of error are things that you know
happened and things that could have happened.
For each source of error, you should have three
things:
19

 C h a p t e r
2 • Laboratory Notebooks and Reports
1. Describe in detail the error that could have
occurred.
2. Explain exactly how the error would have affected the results. Do not say “The results would
be skewed.” Be specific and state if results would
be lower or higher than expected.
Chapter
2
Has successfully learned what the lab is designed to
teach
• TA will evaluate your understanding of the topic
based on the overall quality of your report, your
work in the lab, and the information entered into
your lab notebook.
•
Ask questions about concepts you don’t understand.
•
Work with your lab partner to complete the experiment.
•
Include all data and observations in your lab notebook and do so following the guidelines given at
the beginning of this chapter.
3. Explain how the error could have been
prevented.
•
•
Example: Loss of sample on the filter paper would
have resulted in a lower mass of product. This
would have caused the mass percent of copper in
the final formula to be lower than the theoretical
value. This could have been prevented by transferring the sample more carefully from the filter paper
into the beaker.
Addressing sources of error requires a critical review
of each step of the experiment rather than saying
“I messed up” or “we didn’t know what we were
doing.”
Conclusion
The conclusion gives you the opportunity to discuss
what you learned in this experiment. It can be written
in first person (i.e., “I learned…”). This is also an opportunity for the TA to evaluate your understanding of
the experiment and related concepts through your work
in the lab, how you worked with your lab partner, and
through an evaluation of your lab notebook.
Convincingly describes what has been learned in the lab
• State what you have learned and how it relates to
other topics or to real-life situations.
 20
•
Give any reasonable suggestions for improving the
experiment.
•
You should not describe your lab partner’s ability
or inability to function in a lab setting.
Presentation
Whenever you are submitting your work to someone
else to read, you should pay attention to the general
appearance and formatting. Remember that your TA
will be reading your report on a computer screen so you
want to make sure it is legible and easy to read.
When referencing other sources, you should use the
MLA style. Some simple examples are shown below, but
if you have questions refer to a style guide. Additional
help is available in the Writing Center (more information at http://www.uky.edu/AS/English/wc/).
Original Text from Advanced Inorganic Chemistry by
F. Albert Cotton and Geoffrey Wilkinson
Crystalline hydrates of metal ions and of organic substances, especially those with N–H and O–H bonds, are
numerous. For metal ions, the oxygen is always bound
to the metal and the lone pairs on it can be directed
toward the metal and involved in bonding but can,
however, also form H bonds.
Paraphrase and In-Text Citation
Many metal ions can form crystalline hydrates (Cotton 96).
C h a p t e r
Quotation and In-Text Citation
For the crystalline hydrates of “metal ions, the oxygen
is always bound to the metal” (Cotton 96).
•
References should have all the necessary information.
•
Include an alphabetized list of references at the end
of your report.
•
When referencing a Web site, follow the style above
and include the month and year the page was accessed.
or
Cotton states that for the crystalline hydrates of “metal
ions, the oxygen is always bound to the metal” (96).
Bibliography/Works Cited
Book with one or more authors
Author(s). Title of Book. Place of Publication: Publisher,
Year of Publication.
Example
Cotton, F. Albert & Geoffrey Wilkinson. Advanced Inorganic Chemistry. New York: John Wiley & Sons, 1988.
Web Site
Before you use a Web site as a reference, make sure you
evaluate the quality of the content. Just because it is
posted on the internet doesn’t mean it is true.
Use of Wikipedia has its place, but is not appropriate
for information that can be found in your textbook or
this lab manual.
Author(s). Name of Page. Date of Posting/Revision. Name
of institution/organization affiliated with the site. Date
of access <electronic address>.
For additional information on the MLA style, check out
the following resources:
• h t t p : / / o w l . e n g l i s h . p u r d u e . e d u / o w l /
resource/557/01/
2 • Laboratory Notebooks and Reports •
Use the correct type of arrows in all reactions.
•
Use Equation Editor when typing mathematical
formulas.
•
Follow any guidelines for margins, fonts, etc. as
given by your TA (see page 23).
2
Report Is Written in Scientific Style
• All statements and explanations are logical.
•
Make sure that relationships between theoretical
concepts are clear.
•
Do not include unnecessary information (i.e., “This
report isn’t very good because I was out of town this
weekend” or “I couldn’t complete the calculations
because I didn’t write down my data and my lab
partner didn’t send it to me.”).
Do not repeat information unless it adds some value
or insight to the concepts discussed in the report.
•
•
Use third person in the report (first person is acceptable only in the conclusion).
Citations and References Are Formatted Correctly
• In-text citations are included for any paraphrased or
quoted material. Remember that direct quotations
must have quotation marks and a reference.
•
Proofread your report before submitting. It is usually best to let it sit for a day (or at least a few hours)
and then reread the report. You might catch errors
in grammar or spelling or realize that you omitted
some important information.
•
Chapter
Formatting of Reports Is Correct
• Use subscripts and superscripts in chemical and
mathematical formulas.
http://www.bedfordstmartins.com/online/
cite5.html
•

In-text citations should include author’s name and
page number.
21

 C h a p t e r
2 • Laboratory Notebooks and Reports
Grammar and Spelling
• Proofreading your report, perhaps out loud, will
help you detect grammatical errors.
•
A list of common grammatical errors can be
found at http://bcs.bedfordstmartins.com/
everyday_writer3e/20errors/ or search on an
internet search engine such as www.google.com
for “common errors in grammar.”
•
Since all reports are typed on a computer, use
the spell-check feature in your word processor.
For words not in the standard dictionary, such as
chemical names, look them up in your lab manual,
textbook, or use an internet search engine such as
www.google.com to find the correct spelling.
•
Make sure all sentences are complete sentences and
have subject-verb agreement.
•
If you need help with your writing skills, visit the
Writing Center on the 5th floor of the W. T. Young
library. More information about the Writing Center can be found at http://www.uky.edu/AS/
English/wc/. You can go to the Writing Center
for help or use some of their online resources (look
under “Student Resources”).
Chapter
2
 22
C h a p t e r
2 • Laboratory Notebooks and Reports Semester and Year
________________________________________________________________________
Room Number
CP- 
Information About My TA
Name (first and last) ________________________________________________________________________
Chapter
Contact Information ________________________________________________________________________
(e-mail and/or phone)
Office Hours
________________________________________________________________________
All office hours are held in CP-25, the General Chemistry Learning Center.
Other Information
________________________________________________________________________
2
Formatting Preferences for Lab Reports
Ask your TA the following questions so that you know exactly what they want. Since they are the one grading
your report, it is in your best interest to follow their formatting preferences. If they request something specific and
you do not know how to do it, you can ask them or look in the help files of your word processing program.
1.
Do you have a preference for single or double-spacing?
2.
Do you prefer a particular font? What about font size?
3.
What size margins do you prefer?
4.
Do you want a separate title page or can the title be at the top of the first page?
5.
Should references be listed on a separate page or can they be placed at the end of the conclusion?
6.
Do you have any preference for formatting tables, such as showing all gridlines?
7.
Do you have any other preferences for the format of lab reports?
23

 C h a p t e r
Chapter
2
 24
2 • Laboratory Notebooks and Reports

C
h
a
p
t
e
r
3
Techniques for General Chemistry Lab
One of the goals of this course is to teach students some basic laboratory techniques
that they will use in this course as well as in future laboratory courses. Using correct
techniques is important for several reasons. Proper technique:
1.
reduces the error in experimental results.
2.
prevents damage to equipment.
3.
prevents contamination of reagents.
4.
helps maintain a safe environment in the lab.
Dispensing Solids
Reactions are performed using reagents in both the liquid and solid phase so it is important to know how to dispense solids from the stock reagent bottle. The following
steps should be performed when dispensing solids from a reagent bottle:
1.
Obtain a small beaker, watch glass, or weigh boat to transfer the solid reagent.
2.
Determine the approximate amount of the solid needed.
3.
Locate the stock reagent bottle.
4.
Remove the lid and lay it top-down or hold the lid. Never lay lids facedown as this
can lead to contamination of the stock reagent.
5.
Pour the approximate amount of solid needed into your container. Rotate the bottle
slowly to help pour the sample slowly without getting too much.
25

 C h a p t e r
6. Replace the lid on the reagent bottle and take your
sample to your bench or the balance area.
Some additional tips for dispensing liquid reagents.
• Never return excess reagents to the stock bottle.
Some additional tips for dispensing solid reagents.
• Whenever dispensing solids, you should be careful
not to create a “dust cloud” of the chemical to avoid
inhalation and eye exposure.
•
Wipe up any spills to avoid any injuries when
someone else comes to the stock reagent area.
•
Never insert a dropper or any other object into the
stock reagent bottles in order to prevent contamination.
•
Always leave stock reagent bottles in their original
location so that everyone has access to them.
•
Concentrated acids and bases should be used in the
hood. Do not remove the bottles from the hoods.
•
The brown dropper bottles used for concentrated
acids and bases should be tilted to dispense the
reagent. Do not remove the lid.
•
Chapter
3
3 • Techniques for General Chemistry Lab
•
Always leave stock reagent bottles in their original
location so that everyone has access to them. Never
take reagent bottles to the balance area or to your
bench.
Never insert a spatula or any other object into the
stock reagent bottle in order to prevent contamination.
Dispensing Liquids
Liquids tend to be easier than solids to obtain since
they are easier to pour and it is easier to estimate the
volume of a liquid than the mass of a solid. The following steps should be performed when dispensing liquid
from a reagent bottle:
1. Obtain a small beaker or test tube to transfer the
liquid reagent.
2. Determine the approximate amount of reagent
needed.
3. Locate the stock reagent bottle.
4. Remove the lid and lay it top-down or hold the
lid. Never lay lids facedown as this can lead to
contamination of the stock reagent.
5. Pour the approximate amount needed into your
container. Measure the exact volume needed when
you return to your bench. If you take the time to
measure exact volumes at the stock reagent area,
you cause delays for other students.
6. Replace the lid on the reagent bottle and take your
sample to your bench.
 26
Using an Analytical Balance
The analytical balance is often used in many chemistry laboratories. It allows us to determine the mass of
a substance. Although the terms mass and weight are
frequently used interchangeably, they are not the same
thing. Mass is the amount of something while weight
is a measure of the pull of gravity on the object. Mass
is independent of location, while weight is not. The
mass of an object on the moon will be identical to its
mass on Earth. The weight of an object will change. For
example, a 100-pound object on Earth will weigh 16.5
pounds on the moon and 234 pounds on Jupiter.
Most labs use electronic analytical balances but some
still use what is known as a triple beam balance. The
General Chemistry Labs use electronic analytical balances which look similar to that shown in Figure 3.1.
To increase the accuracy of your measurements, always
use the same balance throughout an experiment.
1. Turn the balance on and check that all doors are
closed or cover is on.
2. Press the “0/Tare” button to set the balance to
zero.
C h a p t e r
©Hayden-McNeil, LLC
•
Use a weigh boat (see Figure 3.2) or a small beaker
to hold the sample.
•
Never pour reagents into a container in the balance.
Always remove the container, add the reagent, and
then place in the balance.
•
Record all digits given on the display so that you
can keep as many significant figures as possible after
your calculations.
•
Display
3 • Techniques for General Chemistry Lab

Chapter
3
Always clean the balance after each use.
Balance pan
Figure 3.1. Electronic analytical balance.
©Hayden-McNeil, LLC
Tare means to adjust the zero point on a balance
Figure 3.2. Weigh boat.
3.
Place the object on the balance pan and close the
doors or replace the cover.
4.
Allow the value to stabilize and record all digits on
the display in your lab notebook.
5.
Remove the sample from the balance.
6.
Use the brush to remove any solids from the balance.
7.
Close the doors or replace the cover and turn off
the balance.
Some additional tips for using an electronic analytical
balance:
•
Balances are fragile pieces of equipment. You should
not move a balance except when necessary. Always
open and close cover gently.
•
•
Never take reagent bottles to the balance area. Get
the approximate amount needed in a beaker or
other container and take that to the balance area.
Never return excess reagent to the stock bottle. If
you have excess reagent, offer it to someone else or
dispose of it correctly. Do not leave it in the reagent
area or near the balances.
Using a Graduated Cylinder
One piece of glassware commonly used in lab is a graduated cylinder which is used to measure the volume of
liquids needed. Graduated cylinders come in many
sizes, from 10 mL (or smaller) to 4 L. The following
steps should be used when measuring the volume of a
liquid using a graduated cylinder:
1.
Obtain a clean, dry graduated cylinder.
2.
Pour the amount needed into the cylinder.
3.
Record the exact volume used rather than trying to
obtain the volume listed in the procedure.
a.
Look for the bottom of the meniscus (see Figure
3.3). The meniscus will be much less prominent
in plastic than in glass due to differences in the
adhesive interactions between the liquid and
the container.
b.
Position yourself so that your eyes are level
with the meniscus.
c.
Using the markings on the cylinder, determine
the volume of the liquid in the cylinder.
27
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d.
Chapter
3
3
• Techniques for General Chemistry Lab
Always estimate one additional decimal place
beyond the markings of the cylinder when
reading the volume to improve the accuracy
of your value. It is assumed that the last digit
has been estimated.
4.
Add the liquid to the reaction as directed in the
procedure.
5.
Clean the cylinder to prevent contamination with
its next use.
•
Meniscus
Some additional tips for using a graduated cylinder:
•
Always estimate one additional decimal point.
Looking at the example shown in Figure 3.3, we
can see that the volume is between 88 and 89. By
estimating the next digit between these two markings, we increase the accuracy of our measurement.
Since the last decimal place is assumed, someone
seeing a volume of 88 mL would think it is between
80 and 90. If someone sees a volume of 88.6 mL,
then this lets them know the volume is between
88 and 89 which is a far more accurate description
of the volume of the liquid.
•
•
Volumes given in the procedure are approximate.
It is more important to record the actual volume
used rather than spending time trying to get to the
exact volume listed in the procedure.
Use the smallest graduated cylinder that will
contain your sample for increased accuracy. For
example,
o
o
•
 28
Volumetric glassware usually has markings indicating if they are “TD” or “TC,” which stand for “to
deliver” and “to contain.” A temperature is also
listed which indicates the temperature at which the
cylinders are calibrated. If used at a different temperature, there can be some error in the measured
volume.
100
90
Eye level
80
Reading 88.6 mL
70
©Hayden-McNeil, LLC

Figure 3.3. Determining the volume in a graduated cylinder.
Using a Buret
Another piece of volumetric glassware is called a buret.
A buret is often used when the amount of liquid to be
added to the reaction is unknown. The liquid can be
dispensed from the buret as needed and the volume is
determined by recording the initial and final volume of
the buret. To use a buret, do the following:
Use a 10 mL cylinder to measure 3 mL of solution.
1.
Obtain a clean, dry buret, a ring stand, and a buret
clamp.
Use a 50 mL cylinder to measure 18 mL of
solution.
2.
Set up the buret as shown in Figure 3.4.
3.
Close the stopcock (handle should be perpendicular
to the buret). Put a small beaker under the buret in
case there are any leaks.
Never return excess reagent to the stock bottle. If
you have excess reagent, offer it to someone else
or dispose of it correctly.
C h a p t e r
Initial volume
0.40 mL
Buret clamp
3 • Techniques for General Chemistry Lab

0
1
Chapter
23
Final volume
23.80 mL
Ring stand
3
©Hayden-McNeil, LLC
Buret
24
Flask
25
©Hayden-McNeil, LLC
Figure 3.4. Setting up a buret.
4.
Use a funnel and fill the buret with the necessary
solution.
5.
Remove the funnel from the buret.
6.
Open the stopcock (handle should be parallel to the
buret) to allow 1–2 mL of liquid to drain from the
buret. Repeat if there are still air bubbles present
in the tip of the buret.
7.
8.
Record the initial volume (see Figure 3.5). The initial
volume does not have to be at zero. It will save you
time and effort if you just record the initial volume
as it is instead of trying to get the initial volume to
zero. Estimate one decimal place beyond the markings on the buret.
Dispense the amount of liquid needed. Be careful
not to dispense past the bottom markings on the
buret.
Figure 3.5. Reading the initial and final volumes on a buret.
9.
Record the final volume (see Figure 3.5), estimating one decimal place beyond the markings on the
buret. Subtract the initial volume to determine the
volume dispensed.
Some tips on using a buret:
•
The volume markings go from top to bottom.
•
Always estimate one additional decimal point.
By estimating the next digit between these two
markings, we increase the accuracy of our measurement.
•
Remove the funnel and check for air bubbles before
recording the volume.
•
If you need more volume than the buret contains,
record two pairs of initial and final volume data
and combine the differences from the two pairs.
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3 • Techniques for General Chemistry Lab
If you have a broken buret, please take it to your
TA. The tip and stopcock can be replaced and the
barrel can be repaired, depending on the location
of the break.
Gravity Filtration
Separations play an important role in chemistry and
range from separating a solid from a liquid to separating
two isomers of a compound. Gravity filtration is one
of the simplest forms of separation and is used to separate a liquid from a solid. Much like you drain cooked
spaghetti in a colander, a solid can be separated from a
liquid by pouring the sample through a piece of filter
paper in a funnel. Think of the filter paper as a colander
with really, really small holes in it. To perform a gravity
filtration do the following:
Chapter
3
1. Obtain a funnel, filter paper, and flask. If you want
to filter the liquid into a beaker, you would also
need a ring stand and an iron ring.
2. Initial the filter paper with a pencil and find its mass.
3. Fold the filter paper in quarters and then open into a
cone (see Figure 3.6a). Place the cone into the funnel
which can be inserted into the neck of the flask or
placed in a ring over a beaker (see Figure 3.6b).
4. Wet the filter paper with the solvent of the solution
being filtered (commonly distilled water).
5. Using a stirring rod to help, pour the liquid into the
funnel. Then use a wash bottle to wash the remaining sample out of the beaker (see Figure 3.7).
6. Rinse the solid a few times with an appropriate
solvent.
7. Allow the filtration to continue for several minutes
after it appears complete. This allows any additional
solution to filter through which will require less
time for the solid to dry, if applicable.
Some tips for doing a gravity filtration:
• If the solvent used is flammable, use caution when
heating a sample to dry. Liquids such as ethanol and
acetone have low flash points which are the lowest
temperatures at which the vapors of the liquid can
ignite in air. Use caution when placing samples
rinsed with flammable solvents in the oven.
•
Do not overfill the funnel when adding the sample
to the funnel. Make sure the liquid does not go
above the top edge of the filter paper.
Vacuum Filtration
While gravity filtration is effective, it can be slow and
vacuum filtrations are usually much more efficient than
gravity filtrations. A Büchner funnel is one type of funnel that can be used for a vacuum filtration. It is shaped
differently from a regular funnel and has many small
holes instead of one large hole. Rather than waiting for
the liquid to go through the filter paper on its own, a
vacuum filtration pulls the liquid through. A vacuum
can be created in a filtration flask when the filter flask
is connected to a water aspirator. As water flows down
through the faucet, air is pulled in through the side arm
and out of the connected flask. This creates a vacuum
in the flask which then pulls the liquid through the
Büchner funnel and filter paper.
1. Obtain a Büchner funnel, filter flask, vacuum
tubing, filter paper, ring stand, clamp, and clamp
holder.
2. Initial the filter paper with a pencil and find its
mass.
3. Set up the funnel as shown in Figure 3.9 and place
the piece of filter paper in the funnel. The filter
paper should lay flat in the funnel.
4. Connect the vacuum tubing to the side arm of the
aspirator on the faucet (see Figure 3.8).
5. Turn the water on.
8. Remove the filter paper from the funnel, place on
a pre-massed watch glass, and place in an oven to
dry.
 30
6. Use a small amount of the solvent to wet the filter
paper.
3 • Techniques for General Chemistry Lab
C h a p t e r

Crease paper
slightly
Fold in
quarters
Fold in
half
Chapter
3
©Hayden-McNeil, LLC
Open out
into cone
©Hayden-McNeil, LLC
Figure 3.6a. Folding filter paper for gravity filtration.
Figure 3.6b. Setting up for gravity filtration.
Tip of funnel
touches the
beaker wall
©Hayde
n-McN
Figure 3.7. Performing a gravity filtration.
eil, LL
C
31
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C h a p t e r
Chapter
3
3
• Techniques for General Chemistry Lab
7.
Using a stirring rod to guide the solution, pour the
sample to be filtered onto the filter paper. Pour small
portions to avoid getting solid underneath the filter
paper.
8.
Allow the filtration to continue for several minutes
after it appears complete. This allows any additional
solution to filter through which will require less
time for the solid to dry, if applicable.
9.
•
If the solvent used is flammable, use caution when
heating a sample to dry. Liquids such as ethanol and
acetone have low flash points which are the lowest
temperatures at which the vapors of the liquid can
ignite in air. Use caution when placing samples
rinsed with flammable solvents in the oven.
Stirring rod
Disconnect the tubing to break the vacuum before
turning off the water.
10. Use a spatula to help remove the filter paper from
the funnel. Place the filter paper on a pre-massed
watch glass and place in oven to dry.
11. Check the procedure for the experiment to determine whether the filtrate (liquid) should be preserved for additional experiments or disposed of.
Filter paper
Büchner funnel
to aspirator on
water faucet
Filtration flask
LC
l, L
Nei
Mc
 32
en-
Some tips when doing a vacuum filtration:
•
If you notice a leak under the sink, disconnect the
vacuum first and then turn off the water. Notify
your TA.
ayd
©Hayden-McNeil, LLC
Figure 3.8. Aspirator connection.
©H
filtrate
Figure 3.9. Vacuum filtration setup.

C
h
a
p
t
e
r
4
Using MeasureNet and Probes
Students will collect data in the lab using the MeasureNet workstation and a variety of
probes. The workstation is the user interface which allows students to set up experiments,
and then collect data which is then uploaded to the Chem21 server where it can later
be retrieved to complete the data analysis for the experiment. The data is displayed on
the workstation display as it is collected. The probes connect to the workstation via the
ports on the bottom of the workstation. Figures 4.1 and 4.2 show a picture of a student
workstation with the buttons divided into groups based on their function as well as the
bottom of the workstation where the probes are connected.
Please be aware that components of electronic data collection systems are expensive
and must be handled with care. Follow the directions carefully to both collect good
data and to protect the equipment.
The TA in the lab will log students into the workstation and can monitor their data collection throughout the lab session. Once logged in, students can begin to collect data.
Do not begin work until your TA has confirmed that you are logged in to the correct
workstation. The instructions on the following pages provide a general outline for use
of the MeasureNet workstation and probes. However, students are expected to adapt
these instructions for the specific experimental needs as they write their procedures.
Carefully read the information on the display as there is sufficient information there
to help guide you to the next step.
33
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4
• Using MeasureNet and Probes
Chapter
4
Figure 4.1. Front view of MeasureNet workstation.
Figure 4.2. Bottom view of MeasureNet workstation.
Operation of the MeasureNet Workstation
 34
1.
Connect the appropriate probe to the workstation.
2.
Press the power button on the workstation and see
that the status is “online.”
3.
Press “MAIN MENU” to see a list of probes.
4.
Use the function keys (F1, F2, etc.) to select the
correct probe.
5.
Use the function keys again to select the appropriate type of experiment (e.g., temperature vs. time,
pressure and temperature, etc.).
6.
When indicated in the probe instructions, select
“CALIBRATE” and follow the directions on the
display.
7.
Choose “SETUP” to specify limits of the axis (i.e.,
the probable range of your data) for display purposes. Values outside these limits will still be collected
but will not appear on the workstation display.
a.
After data collection is complete, you can
change the limits to replot the current data set.
C h a p t e r
4 • Using MeasureNet and Probes 
8. Use the arrows to highlight (look for asterisks on
either side) the value that needs to be changed, type
in the correct value, and press “ENTER.”
9. Select “DISPLAY” to accept all values.
10. Press “START/STOP” to start data collection. Data
will continue until the x max value or until you
press “START/STOP” again.
pH Electrode and Calibration
For this titration experiment, we will use a pH electrode
to measure the change in pH as we add the standard
solution to our analyte solution. In order to obtain accurate data, the pH electrode must be calibrated against
solutions of known pH. Because we will be measuring
pH values over a wide range, we will calibrate the electrode against two solutions with pH values of 4.0 and
10.0. It is only necessary to calibrate before the first
titration that you perform in lab that day. Changes in
signal from the electrode do change over time but the
change during one lab period is not significant.
The pH electrode is a delicate and expensive piece of
equipment. Use caution to avoid breaking the tip and
do not use it to stir a solution. The only moveable/
removeable part on the electrode is the storage bottle.
Drop Counter
When using the pH electrode, we will also be using a
device known as a drop counter. As each drop of liquid
passes through the “counting slot” with its infrared
beam, it is counted. By entering both the initial and final
volumes on the buret, the average drop size can be determined, which, along with the number of drops, will
allow us to graph a pH vs. volume curve. This titration
curve can then be used to determine the equivalence
point which is then used to determine the concentration of the analyte (unknown) solution.
When using a drop counter, it is imperative that you
set the equipment up correctly and that the solution
dispensed from the buret is done so in drops. If the
buret is opened to allow a constant flow of liquid, the
data will be unusable.
Chapter
Figure 4.3. Drop counter.
4
Calibration
1. Obtain a pH sensor, ring stand, drop counter, and
any needed clamps. Complete the setup of the drop
counter and pH electrode as shown in Figures 4.3
and 4.4.
2. Obtain approximately 20–25 mL of each of the
buffers (pH 4.00 and pH 10.00) in separate plastic
50 mL beakers. These will be used to calibrate the
pH probe and should not be used for any other
purpose.
3. Remove the storage bottle from the pH electrode,
connect it to the workstation, and insert it into the
opening on the drop counter so that the cap rests
in the recess.
4. Rinse the pH electrode with distilled water and collect
the waste into a 250 mL beaker. This will be used as
your waste beaker throughout the experiment.
5. Use a thermometer to measure the temperature of
the pH 4.00 buffer solution and record the value.
6. Place the pH 4.00 buffer solution underneath the
pH electrode and lower the electrode into the
solution.
7. Press “MAIN MENU” on the workstation and select
“pH/mV” from the menu and then select “pH v
Volume.”
35

 C h a p t e r
4 • Using MeasureNet and Probes
8. Select “CALIBRATE” and the workstation will
prompt you to enter the temperature and the correct pH of the solution (e.g., 4.00).
9. Once the pH reading on the screen stabilizes, press
“ENTER.” The value on the screen may not read
4.00; you are just waiting for the value to stop
changing.
10. When prompted, enter the pH of the second buffer
solution (e.g., 10.00). Remove the electrode from
the first buffer solution and rinse well with distilled
water into your waste beaker.
Chapter
11. Place the beaker with the pH 10.00 buffer below
the electrode and lower it into the solution.
4
12. Once the pH reading on the screen stabilizes, press
“ENTER.” The value on the screen may not read
10.00; you are just waiting for the value to stop
changing.
13. Press “DISPLAY” on the workstation. The pH value
should be within + 0.05 of the actual pH of the
second buffer solution. If not, you need to redo the
calibration.
14. Raise the pH electrode and remove the buffer solution. Rinse the electrode well with distilled water.
Titration
1. Obtain approximately 40–50 mL of your titrant
(usually your solution of known concentration) in
a 100 mL beaker.
6. Open the stopcock to drain enough titrant to fill
the tip (~1–2 mL). At this time, you also need to
determine how far to open the buret so that the
solution drips from the buret. The solution must
drip in order to collect data.
2. Rinse the buret with 3–5 mL of the titrant by pouring it in the buret so that it covers all sides and then
draining it into your waste beaker. Do three rinses.
7. Once you have found where to turn the stopcock
so that the solution will dispense dropwise, close
the stopcock and remove the waste beaker.
3. Attach a buret clamp to the ring stand and insert the
buret so that the tip of the buret is directly over the
“counting slot” on the drop counter. The solution
from the buret must drop through the counting
slot to collect data.
8. Obtain a sample of the analyte (usually the unknown solution). Remember that the larger volume
used, the longer it will take to titrate (<25 mL is
usually a safe place to start). Using a graduated
cylinder, determine the exact volume. Don’t forget
to estimate one decimal place beyond the markings
on the glassware!
4. Place the waste beaker underneath the buret and
close the stopcock.
5. With a funnel, fill the buret with the titrant solution. Remove the funnel.
 36
Figure 4.4. Titration setup.
9. If needed, add distilled water to the beaker so the
total volume (distilled water plus analyte) will be
~40–50 mL of solution in the 150 mL beaker and
then add the known volume of the analyte solution.
C h a p t e r
10. Place the 150 mL beaker underneath the drop
counter and lower the pH electrode into the solution. The pH electrode should be just above the
bottom of the beaker so that you can gently swirl
the solution.
11. Check that the buret tip is directly over the “counting slot” so the drops will go through the opening
and into the beaker. Do not open the stopcock yet.
12. Begin the titration by pressing “START/STOP.” The
workstation will prompt you to enter the initial
volume. Enter the actual volume reading from the
buret. Remember to record the volume to the second decimal place when you estimate one decimal
place beyond the markings on the buret. The buret
does not have to start at zero.
13. Carefully, turn the stopcock on the buret so that the
titrant drips into the analyte solution. You may need
to make small adjustments to the stopcock so that
the solution continues to drip at approximately 1
drop per second. The red LED light will flash each
time it detects a drop.
14. Gently swirl the beaker while the titrant is being
added, being careful to keep the beaker under the
buret at all times.
4 • Using MeasureNet and Probes 
15. Allow the titrant solution to drip into the analyte
solution until the titration is complete. When
complete the pH value will plateau (~10–12 for a
basic titrant and ~1–4 for an acidic titrant).
16. When complete, simultaneously press “START/
STOP” on the workstation and close the stopcock
on the buret.
17. Record the final volume reading in your lab notebook and enter it into the workstation.
18. Continue by saving the data (see directions on page
41).
Chapter
4
19. Refill buret as needed and repeat until experiment
is complete. At least three good titrations should be
collected for each set of needed titrations. This may
mean that you need to collect at least four titrations
so that the outlier can be excluded.
20. Dispose of waste in the appropriate location and
clean all equipment and glassware before returning
it to the correct location.
21. Rinse the pH electrode with distilled water, remove
it from the drop counter, and replace the storage
bottle. The electrode needs to be stored wet in the
storage solution, not in distilled water and never
stored dry. See your TA if you need additional storage solution.
22. Carefully, wipe any liquid from the surfaces of the
drop counter.
Reminders for Use
• Always rinse the probe with distilled water after
each use.
•
Store only in the pH storage solution. Never store
dry or in water.
•
Calibrate at the start of the lab session.
•
Solutions must drop through the drop counter. A
flow of solution will cause errors in your data.
Figure 4.5. Typical titration curve.
37
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4 • Using MeasureNet and Probes
Pressure Probe
The pressure probe can be used to measure the pressure
of the contents in a container. It measures “gauge pressure,” which is the difference in pressure between the
atmospheric pressure and the pressure of whatever is
connected to the probe. Like an open-ended manometer, you need to add the reading from the gauge and
the atmospheric pressure to get the actual pressure. The
atmospheric pressure can be found on the barometer
located in the lab.
4. Press “CALIBRATE” and follow the instructions on
the screen.
5. Press “DISPLAY.”
Measuring Pressure vs. Time
1. Attach the tubing to the connector in the stopper.
2. Prepare, but do not mix, any solutions needed.
3. Mix the solutions and quickly insert the stopper into
the container.
4. Allow data to collect until experiment is complete.
Chapter
4
5. If you do not see an increase in pressure, repeat the
trial and check your system carefully for leaks.
6. Continue by saving the data (see directions on
page 41).
7. Repeat as needed for additional trials.
Reminders for Use
• Do not over-tighten the fittings. Stop when you
feel resistance.
Figure 4.6. Pressure probe.
Calibration
1. Connect the pressure sensor to the workstation
without anything attached to the sensor.
2. Press “MAIN MENU” on the workstation. Press the
appropriate function key to select “PRESSURE.”
3. Use the function keys to select “PRESSURE & TIME.”
•
Do not attempt to remove tubing from sensor.
•
Hot plates are hot; plastic melts. Use caution when
using probes and hot plates at the same time.
Temperature Probe
The temperature probe can be used in the range of
–50°C to 125°C and can be used in a variety of substances. While calibration is necessary to determine an
accurate temperature relative to an external accepted
value, many experiments are more focused on the
Figure 4.7. Pressure probe connections. A. Direct connection of the syringe; B. Four-way stopcock connection;
C. Luer-to-hose barb fitting.
 38
C h a p t e r
change in temperature. In these cases, the absolute temperature is not important as long as the probe behaves
uniformly (i.e., offset by 1°C throughout the range of
measurements).
4 • Using MeasureNet and Probes 
2. Once the experimental setup is complete, press
“START/STOP” on the workstation to begin collecting data.
3. Once data collection is complete, press “START/
STOP.”
4. Rinse the temperature probe with distilled water
and dry. Return to the correct storage location.
5. Continue by saving the data (see directions on page
41).
Chapter
4
Reminders for Use
• Hot plates are hot; plastic melts. Use caution when
using probes and hot plates at the same time.
Figure 4.8. Temperature probe.
Calibration
1. Connect the temperature probe to the MeasureNet
workstation.
2. Press “MAIN MENU” on the workstation. Press the
appropriate function key to select “TEMPERATURE.”
3. Use the function keys to select “TEMP v TIME.”
Colorimeter
A colorimeter can be used to measure the amount of
light of a particular wavelength. Unlike scanning instruments which scan a range of the electromagnetic spectrum (e.g., infrared, visible, X-ray, etc.), a colorimeter
monitors a single wavelength. Light of the appropriate
wavelength is absorbed by the solution. As the concentration of the absorbing species increases, the amount
of light absorbed will increase. Sometimes the value is
reported as the percent transmittance which is inversely
proportional to the absorbance.
4. Obtain a small beaker of ice and water.
5. Insert temperature probe into ice bath and wait
2–3 minutes. Stir constantly and keep temperature
probe from touching beaker.
6. Press “CALIBRATE” and follow instructions on the
screen, entering 0°C as your temperature.
Measuring Temperature
1. Select “SETUP” to check limits which are determined by the range of experimental values you
expect. Data outside this range will still be collected
but will not appear on the display. If necessary,
press the arrow keys to select which variable to edit
(marked by asterisks on either side of value), key in
the new value and press “ENTER.”
Figure 4.9. Colorimeter.
The colorimeters used in the lab are known as dual-beam
colorimeters because there are two beams of light that
will go through two paths inside the colorimeter. One
of the beams will go through a cuvette containing the
solvent or other appropriate solution (cell holder “R”) to
account for any light absorbance by the cuvette and/or
39
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 C h a p t e r
4 • Using MeasureNet and Probes
the solution/solvent. This will be known as the blank or
reference solution. The other beam will go through the
sample (cell holder “S”) being studied so the reported
value will actually be a reporting of the difference in
the amount absorbed between the two samples, which
gives us a direct relationship between the concentration of the light-absorbing species and the amount of
light absorbed. The use of a dual beam also eliminates
variations in the signal due to changes in the intensity
of the light.
R
light
source
Chapter
4
detector
beam
splitter
ratio
S
display
detector
Figure 4.10. Dual-beam schematic.
The color of a substance is determined by its interaction
with light. We can see blue because a sample absorbs
all colors of light except blue, which is reflected. Alternatively, we can see blue because its complementary
color (the color across from it on the color wheel) is
absent from the light.
Calibration
1. Connect the colorimeter to the workstation.
Make sure no other probes are connected to the
workstation.
a. Always record the exact volumes used since it is
unlikely that you will get the exact amounts.
For example, instead of 1.00 mL, you might
have 1.08 mL. It is very important that you
record the exact volume so that your concentrations will be correct in the graph which will
be used to determine the concentration of the
unknown.
8. Prepare solutions as needed for the experiment.
9. Rinse both of the cuvettes twice with the blank
solution. Rinsing involves pouring a small amount
of a solution in a cuvette and pouring it out. This
removes any residual liquids from the cuvette to
make sure the concentration of the solution is not
affected by those residual liquids. Dispose of the
rinsings in the appropriate manner.
10. Fill the cuvettes with the blank solution and cap
the cuvette. Use a lint-free tissue to wipe the sides
of the cuvette being careful to hold the cuvette by
the top to avoid fingerprints on the sides.
11. Place one of the cuvettes with the blank solution in
the cell holder marked “R.” Use care when inserting
the cell in the holder as it is designed to hold the
cuvette by the corners only (see Figure 4.11).
2. After verifying that your TA has logged you in
to the workstation, press “MAIN MENU” on the
workstation.
3. Select “COLORIMETRY/FLUOR/TURB” and then
select “COLORIMETRY.”
4. Use the function key to select the appropriate
wavelength.
5. Select “KINETICS” on the workstation.
6. Obtain the necessary reagents.
7. Prepare your blank or reference solution which
should contain everything except the light absorbing species.
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Cuvette position
Cuvette holder
©Hayden-McNeil, LLC
Figure 4.11. Cuvette holder in colorimeter.
12. Place the second cuvette with the blank solution
in the cell holder marked “S.”
13. Slide the colorimeter lid closed and press “ENTER.”
The minimum and maximum percent transmittance will be adjusted at this time and will take
approximately 10 seconds to complete.
14. After this is complete, select “DISPLAY.”
C h a p t e r
4 • Using MeasureNet and Probes Measuring Absorbance
1. Leave the blank solution in the cell holder marked
“R” and remove the blank solution from the cell
holder marked “S.”
13. Repeat for each of the solutions. Double-check all
values before saving data. If you need to change the
data, use the arrow keys to select a data point and
then key in the new value and press “ENTER.”
2. Rinse the second cuvette with your first solution.
14. Continue by saving the data (see directions below).
3. Fill the cuvette with your first solution and cap the
cuvette. Use a lint-free tissue to wipe the sides of
the cuvette being careful to hold the cuvette by the
top to avoid fingerprints on the sides.
Reminders for Use
• Use care when placing cuvettes into the colorimeter
to avoid scratching the cuvette and to avoid spilling
solution into the colorimeter. While colorimeters
are built to be durable, spilled liquids inside any
electronic equipment can destroy it.
4. Place the sample cuvette into the cell holder marked
“S.” Use care when inserting the cell in the holder.
5. Wait until the value has stabilized and then, in
your lab notebook, record the absorbance for the
solution.
•
Record exact volumes used.
•
Always clean cuvettes with a lint-free tissue and
handle carefully. Natural oils on your skin which
are transferred to the cuvette will interfere with
your results.
6. Pour the solution into a waste beaker.
7. Repeat steps with sample solutions until the absorbance for all have been measured. Leave the reference cuvette in the colorimeter for the duration of
the experiment.
8. Pour the solutions from both cuvettes into a waste
beaker.
Check with your TA to see if you will enter data
now or on Chem21.
Chapter
4
Saving Data
1. After data collection is complete, press “FILE OPTIONS” and choose “SAVE.”
2. Enter the appropriate three digit code (see experiment information for details about what code to
use). The code is important as it allows the data to
be correctly imported into Chem21.
3. Press “ENTER.”
9. Push the “MAIN MENU” key and then select
“OTHER.”
4. Check with your TA to make sure the file was saved
and uploaded correctly.
10. Select “MANUAL ENTRY.”
5. Press “MAIN MENU” to start another trial, if
needed.
11. Key in the value of the exact concentration for your
first solution and press “ENTER.” You will need to
calculate this before entering your values.
Reminders
• Data is saved automatically to Chem21.
12. Key in the value of the absorbance for your first
solution and press “ENTER.”

•
When you log in to Chem21, your MeasureNet
data will be available. Other data (e.g., mass of
substance) will be entered manually into Chem21.
•
Data can also be downloaded from Chem21 for
viewing and processing in an external program.
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 C h a p t e r
Chapter
4
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4 • Using MeasureNet and Probes