Kinetics           Quiz #3             Collision Theory                    Answers

1.         Which of the following are necessary for successful collisions to occur?

I           Favorable collision geometry

II          Sufficient Kinetic energy

III        Large ∆H

A.        I only

B.        I and II only

C.        II and III only

D.        I, II, and III

2.         Collision theory states that

A.        All collisions lead to chemical reactions

B.        Most collisions lead to chemical reactions

C.        Very few reactions involve particle collisions

D.        Effective collisions lead to chemical reactions

3.         A catalyst increases the rate of a reaction by

A.        Increasing the concentration of the reactant(s)

B.        Decreasing the concentration of the reactant(s)

C.        Increasing the activation energy of the overall reaction

D.        Decreasing the activation energy of the overall reaction

4.         Milk is refrigerated in order to slow the rate of decomposition by bacterial action. The decrease in reaction rate is due to

A.        A decrease in surface area

B.        A decrease in ∆H for the reaction

C.        A decrease in the fraction of particles possessing sufficient energy

D.        The introduction of an alternate pathway with greater activation energy

5.         In general, a chemical reaction requiring a large activation energy will proceed

A.        At a fast rate

B.        At a slow rate

C.        Only at a low temperature

D.        Only at low concentrations

6.         Consider the following reaction:

Mg(s)  +  2HCl(aq)       MgCl2(aq)  + H2(g)

As the temperature of the above system is increased, the number of collisions

A.        Increases but fewer are effective

B.        Decreases and fewer are effective

C.        Increases and more are effective

D.        Decreases but more are effective

7.         The minimum amount of energy needed to start a reaction is called the

A.        Activation energy

B.        Energy of a reaction

C.        Entropy of a reaction.

D.        Reaction mechanism energy

8.         When a lit match is touched to the wick of a candle, the candle begins to burn. When the match is removed, the candle continues to burn. In this reaction, the match

A.        Behaves as a catalyst

B.        Supplies activation energy

C.        Is part of the rate-determining step

D.        Lowers the activation energy barrier

9.         Consider the following collisions, each one occurring at the same temperature

Before Collision         Collision           After  Collision

Which one of the following factors explains why collision one is successful while collision two is not successful?

A.        Catalyst

B.        Geometry

C.        Concentration

D.        Kinetic energy

10.       Consider the following factors

I           Reactant particles collide

II          Sufficient kinetic energy is present

III        A favorable geometry exists

IV        Catalysts are present

Which combination of the above factors is required for successful collisions

A.        I only

B.        II and III only

C.        I, II, and III only

D.        I, II, III, and IV

11.       To increase the rate of a reaction, there must be

A.        Decrease in the frequency of collisions

B.        An Increase in the frequency of collisions.

C.        A decrease in the frequency of successful collisions

D.        An increase in the frequency of successful collisions

12.       For collisions to be successful, reactants must have

A.        Favorable geometry only

B.        Sufficient heat of reaction only

C.        Sufficient potential energy only

D.        Sufficient kinetic energy and favorable geometry

13.       Consider the following reaction:

CH4     +     Cl2        CH2Cl2     +     H2

Which answer best describes the activated complex?

Formula                       KE relative to reactants

A.        CH4                 higher

B.        CH4                 lower

C.        CH4Cl2 higher

D.        CH4Cl2 lower

14.       Which of the following would change the value of the activation energy for a heterogeneous reaction?

B.        changing the surface area

C.        changing the reactant concentration

D.        changing the average kinetic energy

15.       Which of the following would change the value of the activation energy for a heterogeneous reaction?

B.        changing the surface area

C.        changing the temperature

D.        changing the average kinetic energy

16.       What happens to the activation energy as the temperature in a reacting system decreases?

A.        the activation energy increases

B.        the activation energy decreases

C.        the activation energy stays the same

D.        the activation energy is converted to kinetic energy

17.       How does the addition of a catalyst increase the reaction rate of an endothermic reaction?

A.        It reduces the ΔH of the reaction.

B.        It increases the ΔH of the reaction.

C.        It reduces the required activation energy.

D.        It causes the reaction to become exothermic.

18.       Which of the following would result in a successful collision between reactant particles?

A.        particles have sufficient KE

B.        particles convert their entire PE into KE

C.        particles are in an excited state and are catalyzed

D.        particles have sufficient KE and good molecular orientation

19.       A spark causes propane gas to explode. According to the collision theory, the spark:

A.        lowered the Ea

B.        increased the Ea

C.        provided the Ea

D.        acted as a catalyst

20.       Consider the following reaction:

2H2O2(aq)     O2  +  2H2O(l)

A small amount of KI is added and the reaction rate increases. The best explanation is that KI:

A.        is a catalyst

B.        causes more collisions

C.        causes harder collisions

D.        increases the temperature

21.       The reaction temperature is increased. There are:

A.        more collisions and greater collision energy

B.        more collisions but the same collision energy

C.        the same number of collisions and greater collision energy

D.        the same number of collisions but the same collision energy

22.       A reactant concentration is increased. There are:

A.        more collisions and greater collision energy

B.        more collisions but the same collision energy

C.        the same number of collisions and greater collision energy

D.        the same number of collisions but the same collision energy

23.       A reactant surface area is increased. There are:

A.        more collisions and greater collision energy

B.        more collisions but the same collision energy

C.        the same number of collisions and greater collision energy

D.        the same number of collisions but the same collision energy

24.       In a chemical reaction, which of the following is not true?

A.        most collisions are successful

B.        successful collisions have favourable geometry

C.        successful collisions have sufficient energy

D.        a collision is required