Name: ____________________________________
Class: _____________
Date: _____________
Self Assessment: Collisions in Chemical Reactions
1. The energy of the activated complex in a chemical reaction _____.
a) is lower than that of reactants but higher than that of products
b) is lower than that of reactants and products
c) higher than that of reactants but lower than that of products
d) is higher than that of reactants and products
2. Before they form products, reactants first form _____.
a) more reactants
b) an enzyme
c) new substances
d) an activated complex
3. Magnesium metal reacts with bromine vapor according to the following equation:
Mg(s) + Br2 (g) MgBr2 (s)
Which of the following actions is most likely to increase the rate of this reaction?
a) Reduce the temperature of the reaction.
b) Add oxygen to the bromine.
c) Cut the magnesium into smaller pieces.
d) Reduce the pressure of bromine.
4. According to the kinetic molecular theory, particles of matter _____.
a) are attracted to each other
b) are in the gas phase
c) are in constant motion
d) are molecules of two or more atoms
5. Increasing the temperature of matter increases the number of collisions between particles because _____.
a) the concentration increases
b) the pressure increases
c) the shape of molecules changes
d) the particles move faster
PAGE 1
Name: ____________________________________
Class: _____________
Date: _____________
Self Assessment: Collisions in Chemical Reactions
6. In order for two particles of matter to react when they collide, they must have enough energy and _____.
a) be in the right orientation
b) be uncombined atoms
c) have a high concentration
d) have a low temperature
7. Hydrogen can be generated in the laboratory by reacting zinc metal with dilute sulfuric acid according to
the following equation:
Zn(s) + H2 SO4 (aq) H2 (g) + ZnSO4 (aq)
Grinding the zinc into small pieces will increase the rate of the reaction because _____.
a) the frequency of collisions decreases
b) the concentration of H2 SO4 increases
c) more surface area is exposed
d) the activation energy becomes lower
8. Increasing the concentration of a gaseous reactant results in _____.
a) more molecules of gas in the same space
b) collisions occurring less frequently
c) a reduction in reaction rate
d) an increase in activation energy
9. Reactant particles can form an activated complex when they collide with enough force to _____.
a) increase the temperature
b) decompose into separate atoms
c) change from one element to another
d) allow electrons to be transferred
10. Which of the following statements best describes the usual effect of a 10% increase in temperature on the
rate of a chemical reaction?
a) The reaction rate increases by 1%.
b) The reaction rate doubles.
c) There is no effect on reaction rate.
d) The reaction rate increases by 10%.
PAGE 2
ANSWER KEY
1. d
2. d
3. c
4. c
5. d
6. a
ANSWER KEY Page 1
7. c
8. a
9. d
10. b