MULTIPLE CHOICE QUESTIONS
1A Fall 05
According to the Collision Model of reaction rate, the rate of a reaction
a. increases when temperature increases, in part because a larger fraction
of molecules have enough energy to react.
b. is unaffected by temperature change, because activation energy does
not change with temperature.
c. decreases when temperature increases, in part because ΔE for
reactions decreases.
d. may increase or decrease as temperature changes, depending on
whether ΔE is positive or negative.
Which of the following is a way to find the rate of the reaction: A B?
a. Graph [A] versus time and find the negative slope.
b. Graph [A] versus time and find the y-intercept.
c. Graph [A] versus [B] and find the negative slope.
d. Graph [A] versus [B] and find the y-intercept.
3A Fall 05
1. A spontaneous process
a. is reversible.
b. is irreversible.
c. may be reversible or irreversible depending on whether equilibrium is
maintained throughout the process.
d. may be reversible or irreversible depending on the value of ΔS.
2. Which of the following processes should have ΔS < 0 ?
a. CaCO3(s) CaO(s) + CO2(g)
b. H2O(s) H2O(g)
c. 2 NO2(g) N2O4(g)
d. NaCl(s) + H2O(l) NaCl(aq)
3. The Third Law of Thermodynamics states:
a. If object A is in thermal equilibrium with object B, and object B is in
thermal equilibrium with object C, then object A is in thermal equilibrium
with object C.
b. The entropy of the universe increases for reversible processes.
cΔS = 0 for a pure element in its most stable state at standard conditions.
d. S = 0 for a perfect crystal of a pure substance at 0 K.
5. Consider a process for which ΔH = 211 kJ and ΔS = -57 J/K. How will raising
the temperature affect ΔG for this process?
aΔG will increase
bΔG will decrease
cΔG will not change
d. The effect on ΔG cannot be predicted from the information given.
8. When heat is added to a pure liquid
a. the temperature increases and the entropy is unchanged.
b. the temperature increases and the entropy increases.
c. the temperature increases and the entropy decreases.
d. the temperature is unchanged and the entropy increases.
Spring 06 exam 1
4. A reaction was found to be zero order in B. Increasing the concentration of B
by a factor of 3 would cause the reaction rate to
a) decrease by a factor of 9.
b) increase by a factor of 27.
c) increase by a factor of 3.
d) remain constant.
6. The mechanism for formation of the product X is
A + B C + D (slow)
B + D X (fast)
Which of the following is an intermediate in the reaction?
a) A
b) B
c) C
d) D
8. Which one of the following is true?
a) The rate-limiting step in a reaction is the fastest step in the reaction.
b) Rates of reaction can be either positive or negative.
c) The law of mass action gives the relationships between the
concentrations of reactants and products of a system at equilibrium.
d) A catalyst is a substance which is formed and consumed during a
reaction.
Spring 06 exam 3
1. Which one of the following process has ΔS > 0?
a) 2H2(g) + O2(g) 2H2O(g)
b) 2NO2(g) N2O4(g)
c) BaF2(s) Ba2+(aq) + 2F–(aq)
d) CO2(g) CO2(s)
2. A reversible process is one that
a) is spontaneous in both directions.
b) occurs without any outside interventions.
c) must be carried out at low temperature.
d) can be reversed with no net change in either system or surroundings.
3. The following are state functions EXCEPT
a) H – enthalpy
b) q – heat
c) E – internal energy
d) S – entropy
4. Which one of the following is true?
a) Entropy increases when a liquid freezes at its melting point.
b) For a spontaneous process ΔG > 0.
c) The number of microstates available to a system is a measure of its
entropy.
d) Entropy of the pure crystalline solid is zero at 0C.
Fall 06 3A
2. (3pts) Sodium reacts violently with water according to the equation below.
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
The resulting solution has a higher temperature than the water prior to the
addition of sodium. What are the signs of ∆H° and ∆S° for this reaction?
A) ∆H° is negative and ∆S° is negative
B) ∆H° is positive and ∆S° is negative
C) ∆H° is negative and ∆S° is positive
D) ∆H° is positive and ∆S° is positive
Exam 1 Spring 07
9. (4 pts) The decomposition of hydrogen peroxide in the presence of iodide ion
is believed to occur via the mechanism
H2O2(aq) + I–(aq) H2O(l) + IO–(aq)
H2O2(aq) + IO–(aq) H2O(l) + O2(g) + I–(aq)
In this mechanism, I–(aq) is
a) a catalyst.
b) a reactant in the overall reaction.
c) the activated complex.
d) a product of the overall reaction.
e) an intermediate.
1. (4 pts) If the rate law for a reaction is rate = k [A][B]2. Which one of the
following statements is NOT correct?
a) The reaction is first order in A.
b) The reaction is second order in B.
c) The reaction is second order overall.
d) If [B] is doubled, the reaction rate will increase by a factor of 4.
e) If [A] is doubled, the reaction rate will also be doubled.
2. (4 pts) The overall reactions and rate laws for several reactions are given
below. Which one of the following represents an elementary step?
a) 2A P rate = k[A]
b) A + B P rate = k[A][B]
c) A + 2B P rate = k[A]2
d) A + B + C P rate = k[A][C]
e) A + 2B P rate = k[A][B]
3. (4 pts) The rate law of the following overall reaction A + B C is measured
to be rate = k[A]2. Which one of the following will NOT increase the rate of the
reaction?
a) increasing the concentration of reactant A
b) increasing the concentration of reactant B
c) increasing the temperature of the reaction
d) adding a catalyst for the reaction
e) All of these will increase the rate.
SPRING 07 Exam 3
4. (3 pts) When a system is at equilibrium, ________________.
a) the forward and the reverse processes are both spontaneous
b) both forward and reverse processes have stopped
c) the forward process is spontaneous but the reverse process is not
d) the process is not spontaneous in either direction
e) the reverse process is spontaneous but the forward process is not.
14. (3 pts) Which one of the following has the greatest entropy?
a) 1 mol N2(g) at 1 atm and at 400oC.
b) 1 mol N2(g) at 0.5 atm and at 400oC.
c) 1 mol N2(g) at 0.5 atm and at 700oC.
d) 2 mol N2(g) at 0.5 atm and at 700oC.
15. (3 pts) Which one of the following reactions is spontaneous at all
temperatures?
a) CO2(s) CO2(g) ΔH = +25.1 kJ
b) 2 NCl3(g) 3 Cl2(g) + N2(g) ΔH = –460 kJ
c) 2 NF2(g) N2F4(g) ΔH = –85 kJ
d) all of the above are spontaneous at all temperatures
e) none of the above