Monday, October 15th
Today:
Begin Chapter 6
Frequency: CD
1
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
1
Chemical Reactions
A chemical reaction
 involves the rearrangement of
atoms.
 produces one or more new
substances.
 can be observed by the
appearance of new physical
properties.
A chemical reaction forms new
products with different properties.
An antacid (NaHCO3) tablet
in water forms bubbles of carbon
dioxide (CO2).
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
2
Writing a Chemical Equation
A chemical equation tells us what substances react
(reactants) and what substances are formed
(products).
C(s) + O2(g)
reactants
CO2(g)
product
(+) used when there is two or more products or reactants
heat is used to start the reaction
(s) the compound is a solid
(l) the compound is a liquid
(g) the compound is a gas
(aq) aqueous, the compound is dissolved in water
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
3
Equation for a Chemical Reaction
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
4
Balanced Chemical Equations
In a balanced chemical equation, the number of
atoms in the reactants is equal to the number of atoms
in the products for each element.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
5
Balancing Chemical Equations
To balance a chemical equation,
 whole number coefficients are placed in front of
the chemical formulas.
 coefficients in front of a molecule represent the
multiple of that molecule needed in a balanced
reaction.
 subscripts are never changed.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
6
Checking a Balanced Equation
Reactants
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Products
Atoms C
1
1
balanced
Atoms H
4
4
Atoms O
4
4
balanced
balanced
Chapter 6, Section 1
7
Guide to Balancing a Chemical
Equation
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
8
Steps to Balancing a Chemical
Equation
Balance the following chemical reaction:
Ethanol (C2H6O) burns in the presence of oxygen
gas(O2) to produce steam (H2O) and carbon dioxide
(CO2) gas.
Step 1 Write an equation using the correct formulas
of the reactants and products.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
9
Steps to Balancing a Chemical
Equation
Step 2 Count the atoms of each element in the
reactants and products.
Reactants Products
© 2013 Pearson Education, Inc.
Atoms of C
2
1
not balanced
Atoms of H
6
2
Atoms of O
3
3
not balanced
balanced
Chapter 6, Section 1
10
Steps to Balancing a Chemical
Equation
Step 3 Use coefficients to balance each element.
Step 4 Check the final equation to confirm it is
balanced.
Create a balance sheet to count atoms of each element.
Reactants Products
© 2013 Pearson Education, Inc.
Atoms of C
2
2
Atoms of H
6
6
Atoms of O
7
7
Chapter 6, Section 1
balanced
balanced
balanced
11
Learning Check
Write a balanced equation for the reaction of nitrogen gas
(N2) with hydrogen gas (H2) to form ammonia gas (NH3).
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
12
Solution
Write a balanced equation for the reaction of nitrogen gas
(N2) with hydrogen gas (H2) to form ammonia gas (NH3).
Step 1 Write an equation using the correct formulas
of the reactants and products.
Step 2 Count the atoms of each element in the
reactants and products.
Reactants Products
© 2013 Pearson Education, Inc.
Atoms of N
2
1
not balanced
Atoms of H
2
3
not balanced
Chapter 6, Section 1
13
Solution
Write a balanced equation for the reaction of nitrogen gas
(N2) with hydrogen gas (H2) to form ammonia gas (NH3).
Step 3 Use coefficients to balance each element.
Step 4 Check the final equation to confirm it is
balanced.
Reactants Products
© 2013 Pearson Education, Inc.
Atoms of N
2
2
Atoms of H
6
6
Chapter 6, Section 1
balanced
balanced
14
Equations with Polyatomic Ions
When balancing equations with polyatomic ions that
remain the same on both sides of the equation,
balance them as a unit.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
15
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
16
Combination Reaction
In a combination reaction, two or more
elements (or simple compounds) combine to
form one product.
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Chapter 6, Section 1
17
Decomposition Reaction
In a decomposition reaction, one substance
splits into two or more simpler substances.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
18
Single Replacement Reaction
In a single replacement reaction, one element
takes the place of a different element in a
reacting compound.
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Chapter 6, Section 1
19
Double Replacement Reaction
In a double replacement reaction, the two
positive ions in the reacting compounds
exchange places.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
20
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.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
21
Summary Reaction Types
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
22
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.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
23
Oxidized or Reduced?
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
24
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.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
25
Oxidation and Reduction,
Formation of CaS
Adding the two reactions, oxidation and
reduction, gives us the overall reaction.
The overall reaction is written as:
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
26
Zn and Cu2+
When zinc is added to copper(II) sulfate, zinc undergoes
oxidation, while copper undergoes reduction.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
27
Learning Check
Identify each of the following reactions as
oxidation or reduction.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
28
Solution
Identify each of the following reactions as
oxidation or reduction.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
29
Learning Check
Identify the substances that are oxidized and reduced in
each of the following reactions.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
30
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)
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
31
Characteristics of Oxidation and
Reduction
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Chapter 6, Section 1
32
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
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
33
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).
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
34
A Mole of Sulfur
1 mole of sulfur contains Avogadro’s number of
atoms.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
35
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.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
36
Number of Particles in One Mole
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
37
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:
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
38
Learning Check
How many moles of CO2 are in 2.50 x 1024
molecules of CO2?
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
39
Solution
How many moles of CO2 are in 2.50 x 1024
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.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
40
Solution
How many moles of CO2 are in 2.50 x 1024
molecules of CO2?
Step 3 Use Avogadro’s number to write
conversion factors.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
41
Solution
How many moles of CO2 are in 2.50 x 1024
molecules of CO2?
Step 4 Set up the problem to calculate the
number of particles.
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
42
Subscripts State Atoms and
Moles
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
43
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:
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
44
Guide to Calculating Moles
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
45
Learning Check
How many O atoms are in 0.150 mole of aspirin,
C9H8O4?
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
46
Wednesday, October 17th
Written Quiz
Nerd Nite This Thursday at Crow Peak Brewing
Co.
47
© 2013 Pearson Education, Inc.
Chapter 6, Section 1
47