Reviewing Vocabulary
1. Reactant, Product
The bonds in reactants are broken, and the
new bonds form to make products in a
chemical reaction.
2. Law of conservation of mass, chemical reaction
Matter can not be created or destroyed
during a chemical reaction so the law of
conservation of mass is upheld.
3. Endothermic, Exothermic
Endothermic reactions absorb energy whereas
exothermic reactions release energy.
Reviewing Vocabulary
4. Respiration, photosynthesis
Photosynthesis is an endothermic process.
The overall process that occurs during
photosynthesis can be considered the reverse
of the overall process that occurs during
respiration, which is exothermic.
Reviewing Key Concepts
5. During a chemical reaction, reactants always
D. Form Products
6. The splitting of water molecules into hydrogen and oxygen
molecules is an example of a
B. Chemical Change
7. Combustion reactions
D. Require Oxygen
8. Which of the following will increase the rate of a reaction?
A. Breaking solid reactants into smaller pieces
Reviewing Key Concepts
9. What does a catalyst do in a chemical reaction?
B. It speeds the reaction up
10. During a chemical reaction, the total amount of mass present
D. Does not change
11. Chemical equations show summaries of
C. Chemical Reactions
12. A chemical equation must
B. Be Balanced
13. What type of reaction occurs if the reactants have a greater total bond energy
than the products?
A. An endothermic reaction
14. Endothermic reactions always
A. Absorb Energy
Short Answer
15. Describe the difference between physical and chemical changes. How
can they be identified?
A physical change alters the physical characteristics of a substance, but not
the substance itself. A chemical change, through a chemical reaction,
produces a different substance. Chemical changes can be identified by
color or temperature change, or formation of a gas or precipitate.
16. Compare and contrast the overall chemical reactions of
photosynthesis and respiration. How can these reactions be described in
terms of bond energy in reactants and products?
Overall, they are opposite processes. In photosynthesis, the bond energies
of the reactants are greater than the bond energies of the products. The
process is endothermic. In respiration, the bond energies of the reactants
in the overall chemical reaction are less than those of the products of the
overall reaction. As a result, the overall process of respiration is
exothermic.
Short Answer
17. Describe an example of an advance in technology that makes use of a
chemical reaction.
The reaction that purifies silicon, the reactions in catalytic converters, or
the reaction involving photoresist.
18. When you balance a chemical equation, why can you change
coefficients of the reactants or products but not the subscripts?
Changing the coefficients changes the amount of the substances
(molecules). Changing the subscripts changes the formula of a substance,
which makes it a whole new substance.
EXAMPLE: 2H2O
vs. H4O2
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