Chemical Reaction

Transcription

Chemical Reaction

Types of Reactions
Chemical reactions can be classified as
 combination reactions,
 decomposition reactions,
 single replacement reactions,
 double replacement reactions, or
 combustion reactions.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
1
Combination Reaction
In a combination reaction, two or more
elements (or simple compounds) combine to
form one product.
2
Decomposition Reaction
In a decomposition reaction, one substance
splits into two or more simpler substances.
3
Single Replacement Reaction
In a single replacement reaction, one element
takes the place of a different element in a
reacting compound.
4
Double Replacement Reaction
In a double replacement reaction, the two
positive ions in the reacting compounds
exchange places.
5
Combustion Reaction
In a combustion reaction, a carboncontaining compound that is the fuel burns in
oxygen from the air to produce carbon dioxide
(CO2), water (H2O), and energy in the form of
heat or a flame.
6
Summary Reaction Types
7
Everyday Oxidation–Reduction
Reactions
In an oxidation–reduction
reaction,
 electrons are transferred from
one substance to another.
 if one substance loses
electrons, another substance
must gain electrons.
 energy is provided to us from
food.
 electrical energy is provided in
batteries.
 iron rusts.
8
Transfer of Electrons
In oxidation–reduction reactions,
 the process of losing electrons is called
oxidation.
Oxidation Is a Loss of electrons.
(OIL)
 the process of gaining electrons is called
reduction.
Reduction Is a Gain of electrons.
(RIG)
9
Oxidation and Reduction
10
Oxidized or Reduced?
11
Oxidation and Reduction,
Formation of CaS
In the reaction:
 the reactant, Ca has a charge of 0 and the
product, CaS contains a Ca2+ ion.
 calcium loses two electrons, meaning
oxidation has taken place.
 the reactant, S has a charge of 0 and the
product, CaS contains an S2− ion.
 sulfur gains two electrons, meaning
reduction has taken place.
12
Oxidation and Reduction,
Formation of CaS
Adding the two reactions, oxidation and
reduction, gives us the overall reaction.
The overall reaction is written as:
13
Zn and Cu2+
When zinc is added to copper(II) sulfate, zinc undergoes
oxidation, while copper undergoes reduction.
14
Learning Check
Identify each of the following reactions as
oxidation or reduction.
15
Solution
Identify each of the following reactions as
oxidation or reduction.
16
Learning Check
Identify the substances that are oxidized and reduced in
each of the following reactions.
17
Solution
Identify the substances that are oxidized and
reduced in
each of the following reactions.
1. Mg is oxidized.
Mg(s)
Mg2+(aq) + 2e−
H+ is reduced. 2H+(aq) + 2e−
H2(g)
2. Al is oxidized. 2Al(s)
2Al3+(s) + 6e−
Br is reduced. 3Br2(l) + 6e−
6Br−(s)
18
Characteristics of Oxidation and
Reduction
19
Counting Units
Counting terms are used to describe specific
quantities.
 1 dozen donuts
= 12 donuts
 1 ream of paper
= 500 sheets
 1 case = 24 cans
20
A Mole of Atoms
A mole is a counting unit that contains
 the same number of particles as there are
carbon atoms in 12.0 g of carbon 12C.
 6.02 x 1023 atoms of an element (Avogadro’s
number).
21
A Mole of Sulfur
1 mole of sulfur contains Avogadro’s number of
atoms.
22
A Mole of a Compound
A mole
 of a covalent compound has Avogadro’s
number of molecules.
 of an ionic compound contains Avogadro’s
number of formula units.
23
Number of Particles in One Mole
24
Avogadro’s Number as an
Equality
Avogadro’s number (6.02 x 1023) can be written
as an
equality and two conversion factors.
Equality:
Conversion Factors:
25
Learning Check
How many moles of CO2 are in 2.50 x 1024
molecules of CO2?
26
Solution
molecules of CO2?
Step 1 State the given and needed
quantities.
Given
Need
Analyze
the
Problem.
24
2.50 x 10
molecules of CO2
moles of CO2
Step 2 Write a plan to convert moles to
atoms or
molecules.
27
Solution
molecules of CO2?
Step 3 Use Avogadro’s number to write
conversion factors.
28
Solution
molecules of CO2?
Step 4 Set up the problem to calculate the
number of particles.
29
Subscripts State Atoms and
Moles
30
Moles of Elements in a Formula
The subscripts in a formula give
 the relationship of atoms in the formula and
 the moles of each element in 1 mole of a
compound.
Glucose
C6H12O6
31
Conversion Factors from
Subscripts
Subscripts used for conversion factors relate
moles of each element in 1 mole of a compound
For aspirin, C9H8O4, can be written as:
32
Guide to Calculating Moles
33
Learning Check
How many O atoms are in 0.150 mole of aspirin,
C9H8O4?
34
Molar Mass
Molar mass is
 the mass of one mole
of a substance.
 the number of grams
that equals the atomic
mass of that element.
Molar mass is rounded to
the tenths (0.1 g) place
for use in this text.
35
Guide to Calculating Molar Mass
36
Molar Mass of CaCl2
We calculate the molar mass of CaCl2 to the nearest
0.1 g as follows.
Analyze the Problem.
Given
Need
formula unit CaCl2 molar mass of Ca, Cl; CaCl2
Step 1 Obtain the molar mass of each element.
37
Molar Mass of CaCl2
We calculate the molar mass of CaCl2 to the nearest
0.1 g as follows.
Step 2 Multiply each molar mass by the number of
moles (subscript) in the formula.
Grams from 1 mole of Ca
Grams from 2 moles of Cl
38
Molar Mass of CaCl2
We calculate the molar mass of CaCl2 to the nearest 0.1 g
as follows.
Step 3 Calculate the molar mass by adding the
masses of the elements.
39
Learning Check
Determine the molar mass of K3PO4 to 0.1 g.
40
Solution
Analyze the Problem.
Given
Need
formula unit K3PO4
molar mass of K, P, O;
molar mass of K3PO4
Step 1 Obtain the molar mass of each element.
41
Solution
Step 2 Multiply each molar mass by the number
of moles (subscript) in the formula.
Grams from 3 moles of K
42
Solution
Step 3 Calculate the molar mass by adding the
masses of the elements.
43
One-Mole Quantities
32.1 g
55.9 g
58.5 g
294.2 g
342.3 g
44
Group Assignment
45
45
Chemistry and Cooking
 Bisquick
2 Cups Mix
2 Eggs
1 Cup Milk
8 Pancakes
46
46
Next Week
Written Quiz
Finish Chapter 6
47
47

Chemical Reaction

Transcription

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