Transcript Chemical Reaction - Department of Chemistry

Chapter 5
Chemical Reactions and Quantities
5.1 Chemical Changes
Copyright © 2005 by Pearson Education, Inc.
Publishing as Benjamin Cummings
1
Learning Goals
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Identify a change in a substance as a chemical or a physical
change.
Write a balanced chemical equation from the formulas of the
reactants and products for a reaction.
Identify a reaction as a combination, decomposition, replacement,
or combustion reaction.
Define the terms oxidation and reduction.
Use Avogadro’s number to determine the number of particles in a
given number of moles.
Determine the molar mass of a substance and use molar mass to
convert between grams and moles.
Given a quantity in moles of reactant or product, calculate the
moles of another substance in the reaction.
Given the mass in grams of a substance in a reaction, calculate
the mass in grams of another substance in the reaction.
Describe exothermic reactions and factors that affect the rate of a
reaction.
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Physical Change
In a physical change,
• the identity and
composition of the
substance do not
change.
• the state can change
or the material can be
torn into smaller
pieces.
Copyright © 2005 by Pearson Education, Inc.
Publishing as Benjamin Cummings
3
Chemical Change
In a chemical change,
• reacting substances
form new substances
with different
compositions and
properties.
• a chemical reaction
takes place.
Copyright © 2005 by Pearson Education, Inc.
Publishing as Benjamin Cummings
4
Some Examples of Chemical and
Physical Changes
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Learning Check
Classify each of the following as a
1) physical change or 2) chemical change.
A.
B.
C.
D.
E.
____Burning a candle.
____Ice melting on the street.
____Toasting a marshmallow.
____Cutting a pizza.
____Polishing a silver bowl.
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Solution
Classify each of the following as a
1) physical change or 2) chemical change.
A.
B.
C.
D.
E.
2
1
2
1
2
Burning a candle.
Ice melting on the street.
Toasting a marshmallow.
Cutting a pizza.
Polishing a silver bowl.
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Chemical Reaction
In a chemical reaction
• a chemical change
produces one or more
new substances.
• there is a change in
the composition of
one or more
substances.
Copyright © 2005 by Pearson Education, Inc.
Publishing as Benjamin Cummings
8
Chemical Reaction
In a chemical reaction,
• old bonds are broken and
new bonds are formed.
• atoms in the reactants
are rearranged to form
one or more different
substances.
• Fe and O2 form rust
(Fe2O3).
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