Neutralization Reactions

Transcription

Neutralization Reactions
Neutralization Reactions
Ex: HCl + NaOH
NaCl + HOH
These are double replacement reactions
Ions switch partners. Water is formed.
http://www.youtube.com/watch?v=8IRI5gPR5EY&safe=active
Neutralization Forms Water
H+
from acid
+
OH-

from base
H 2O
neutral
This “net” reaction for neutralization is found
on Table I. It is an exothermic reaction.
Forming a Salt
(+) cation from the base
(-) anion from the acid
combine to form a salt.
If equal concentrations of hydrogen ion H+ and
hydroxide ions OH- are mixed, it results in a
neutral solution.
Ex:
.1M LiOH +
.1M HCl =
Neutral Solution
pH = 7
Completing and Balancing
Neutralization Equations
Write charges for ions in acid and base.
 Switch ion partners. (+ ions stay in front!!)
 Do not bring over subscripts except if part
of a polyatomic ion!
 Criss-Cross charges to balance formulas.
 Balance entire equation.


Name the acid, base and salt.
You Try It
Complete equation and balance formulas
 Balance equation.
 Name acid base and salt

Ex: KOH + H2SO4
KOH + H2SO4
HOH + K2SO4
Ex: Mg(OH)2 + HNO3
Mg(OH)2 + HNO3
HOH + Mg(NO3)2
Hydrolysis

Opposite reaction to neutralization
Salt + Water
Acid + Base
Parent Acid/Base

If you know the salt involved you should
be able to determine which acid and base
it would form if water is added.
Salt + Water
Acid + Base
Ex:
NaCl with water (HOH) would form HCl and NaOH
You Try It

Name the “parent” acid and base that
would be produced from these salts.

Ex:
Potassium chloride
Magnesium carbonate
Let’s Practice

Which substance is always a product when
an Arrhenius acid in an aqueous solution
reacts with an Arrhenius base in an
aqueous solution?
(1) HBr
(2) KBr
(3) H2O
(4) KOH

Which word equation represents a
neutralization reaction?
(1) base + acid → salt + water
(2) base +salt → water + acid
(3) salt + acid → base + water
(4) salt + water → acid + base

What are the products of a reaction
between KOH(aq) and HCl(aq)?
(1) H2 and KClO
(2) KH and HClO
(3) H2O and KCl
(4) KOH and HCl

Sulfuric acid, H2SO4(aq), can be used to
neutralize barium hydroxide, Ba(OH)2(aq).
What is the formula for the salt produced
by this neutralization?
(1) BaS
(3) BaSO3
(2) BaSO2
(4) BaSO4

Which compound could serve as a
reactant in a neutralization reaction?
(1) NaCl
(2) CH3OH
(3) KOH
(4) CH3CHO
Answer: 3
Titrations
Purpose:
To determine the concentration of an acid
or base through a neutralization reaction.
Acid/Base Titration
Buret is filled with a
“standard solution” of
known concentration (M).
Erlenmeyer Flask contains
solution of unknown conc..
Indicator (phenolphthalein)
added to the flask.
Acid/Base Titrations
Slowly “titrate” or drip liquid
into flask from buret until
indicator changes color.
This is the “endpoint” or
“equivalence point”.
(Moles H+ = Moles OH-)
Record total volume (V) used
from buret.
Titration Formula
MA x VA = MB x VB
Molarity Acid x Volume Acid = Molarity Base x Volume Base
Titration Applet
http://group.chem.iastate.edu/Greenbowe/se
ctions/projectfolder/flashfiles/stoichiometry
/acid_base.html
You Try It!
A 50 ml sample of .2M HCl is neutralized by
75ml of NaOH. What is the conc. of the base?
HCl
NaOH
.2M x 50ml = MB x 75ml
MB = .13M
Important Note

Multiply acid/base side of equation by
number of H+ or OH- ions it produces
when dissociating!!!

Ex:
H2SO4 produces 2 H+ so you would
multiply the acid side by “2”
You Try It!
How much of a .1M H2SO4 solution is
needed to neutralize 50 ml of a .05 KOH
solution?
H2SO4
KOH
2 x .1M x VA = .05M x 50ml
VA = 12.5 ml
Titration Demonstration
http://www.youtube.com/watch?v=5BZ0MPI
geEE&safe=active
Let’s Practice

During which process can 10.0 milliliters of
a 0.05 M HCl(aq) solution be used to
determine the unknown concentration of a
given volume of NaOH(aq) solution?
(1) evaporation
(2) filtration
(3) distillation
(4) titration

The data collected from a laboratory
titration are used to calculate the
(1) rate of a chemical reaction
(2) heat of a chemical reaction
(3) concentration of a solution
(4) boiling point of a solution
A student completes a titration by adding
12.0 ml of NaOH(aq) of unknown concentration
to 16.0 ml of 0.15 M HCl(aq).
What is the molar concentration of the NaOH(aq)?
(1) 0.11 M
(2) 1.1 M
(3) 0.20 M
(4) 5.0 M