Question 1

Which of the following best describes a chemical system at equilibrium?

Accepted Answer

The forward and reverse reaction rates are equal.

Question 2

Consider the following reaction at equilibrium: $$ \mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)} . If $$additional $$ \mathrm{NO_2$}  is $$added to the system, what will happen according to Le Chatelier's Principle?

Accepted Answer

The equilibrium will shift to the left, producing more $$ \mathrm{N_2O_4} .$$

Question 3

Which of the following is true for a heterogeneous equilibrium?

Accepted Answer

The equilibrium constant expression omits pure solids and pure liquids.

Question 4

For the reaction $$ \mathrm{2SO_2(g) + O_2$(g) \rightleftharpoons 2SO_3(g)} $$, the equilibrium constant $$ K_c  is 4.0 at a $$certain temperature. What is the value of $$ K_c $$ for the reverse reaction?

Accepted Answer

$$ K_c = 0.25 $$

Question 5

A reaction has $$ \Delta G^\circ = 0  at a $$certain temperature. What can be said about the equilibrium constant $$ K  at $$this temperature?

Accepted Answer

$$ K = 1 $$

Question 6

Which of the following changes will increase the rate of a chemical reaction?

Accepted Answer

Adding a catalyst.

Question 7

The rate law for a reaction is $$ 	ext{rate} = k[\mathrm{A}]^2[\mathrm{B}] . If $$the concentration of $$ \mathrm{A}  is $$doubled and $$ \mathrm{B}  is $$halved, by what factor does the rate change?

Accepted Answer

The rate increases by a factor of 2.

Question 8

A first-order reaction has a rate constant $$ k = 0.693 \ \mathrm{min}^{-1} . $$What is the half-life of the reaction?

Accepted Answer

$$ 1.00 \ \mathrm{min} $$

Question 9

Which of the following best explains why increasing temperature generally increases the rate of a chemical reaction?

Accepted Answer

It increases the number of effective collisions between molecules.

Question 10

For the reaction $$ \mathrm{A \rightarrow B} $$, the concentration of $$ \mathrm{A} $$ decreases from 0.80 M to 0.40 M in 10 minutes. If the reaction is first order in $$ \mathrm{A} $$, what is the rate constant $$ k $$? (Use $$ \ln 2 = 0.693 )$$

Accepted Answer

$$ 0.0693 \ \mathrm{min}^{-1} $$

Question 11

A catalyst increases the rate of a chemical reaction by:

Accepted Answer

Lowering the activation energy.

Question 12

Which of the following statements about the equilibrium constant $$ K_c  is $$correct?

Accepted Answer

$$ K_c $$ changes with temperature.

Question 13

For the reaction $$ \mathrm{2HI(g) \rightleftharpoons H_2$(g) + I_2$(g)} $$, the equilibrium concentrations are $$ [\mathrm{HI}] = 0.60 \ \mathrm{M} $$, $$ [\mathrm{H_2$}] = 0.10 \ \mathrm{M} $$, and $$ [\mathrm{I_2$}] = 0.10 \ \mathrm{M} . $$What is the value of $$ K_c $$?

Accepted Answer

$$ 0.028 $$

Question 14

A reaction is carried out in a sealed container. If the volume of the container is decreased, what will happen to the equilibrium position for the reaction $$ \mathrm{2NO_2(g) \rightleftharpoons N_2O_4(g)} $$?

Accepted Answer

The equilibrium will shift toward the side with fewer moles of gas.

Question 15

Which of the following is NOT a factor that affects the rate of a chemical reaction?

Accepted Answer

The color of the reactants.

Question 16

A student is studying the decomposition of hydrogen peroxide: $$ \mathrm{2H_2O_2(aq) \rightarrow 2H_2O(l) + O_2$(g)} . $$She finds that the reaction is much faster in the presence of manganese dioxide. What role does manganese dioxide play in this reaction?

Accepted Answer

It acts as a catalyst.

Question 17

If the rate law for a reaction is $$ 	ext{rate} = k[\mathrm{A}]^0[\mathrm{B}]^1 $$, what is the overall order of the reaction?

Accepted Answer

First order

Question 18

Which of the following best describes the use of an ICE table in equilibrium calculations?

Accepted Answer

It is used to organize initial, change, and equilibrium concentrations.

Question 19

A reaction has $$ \Delta G^\circ = -10.0 \ \mathrm{kJ/mol}  at 298 K. $$What can be said about the value of the equilibrium constant $$ K $$?

Accepted Answer

$$ K \u003e 1 $$

Question 20

A certain reaction is found to be second order overall. Which of the following could be a possible rate law for this reaction?

Accepted Answer

$$ 	ext{rate} = k[\mathrm{A}]^2 $$

Equilibrium and Kinetics: Study Guide for CHE 1102

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