Question 1

In the 'Blue Bottle' experiment, the solution changes from blue to colorless and then back to blue when shaken. What does this demonstrate about chemical equilibrium?

Accepted Answer

At equilibrium, the forward and reverse reactions occur at the same rate, resulting in no net color change.

Question 2

For the reaction $\mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)}$, which of the following statements is TRUE at equilibrium?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 3

Given the reaction $\mathrm{aA + bB \rightleftharpoons cC + dD}$, what is the correct expression for the equilibrium constant $K_c$?

Accepted Answer

$K_c = \dfrac{[C]^c [D]^d}{[A]^a [B]^b}$

Question 4

For the reaction $\mathrm{N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}$, if the initial concentrations of $\mathrm{N_2}$ and $\mathrm{H_2}$ are both doubled, what happens to the value of the equilibrium constant $K_c$?

Accepted Answer

It remains unchanged.

Question 5

Which of the following changes will shift the equilibrium of $\mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)}$ to the right (toward more $\mathrm{NO_2}$) according to Le Chatelier’s Principle?

Accepted Answer

Adding more $\mathrm{N_2O_4}$ to the system.

Question 6

For the reaction $\mathrm{2NOBr(g) \rightleftharpoons 2NO(g) + Br_2(g)}$, the equilibrium constant $K_1$ is given. For the reverse reaction, what is the equilibrium constant $K_2$?

Accepted Answer

$K_2 = 1/K_1$

Question 7

A reaction mixture at equilibrium contains $\mathrm{[A] = 0.2\ M}$, $\mathrm{[B] = 0.3\ M}$, $\mathrm{[C] = 0.4\ M}$ for the reaction $\mathrm{A + 2B \rightleftharpoons 3C}$. What is the value of $K_c$?

Accepted Answer

$K_c = \dfrac{[C]^3}{[A][B]^2}$

Question 8

Which of the following statements about catalysts and equilibrium is correct?

Accepted Answer

A catalyst speeds up the attainment of equilibrium but does not change the equilibrium composition.

Question 9

For the reaction $\mathrm{CaCO_3(s) \rightleftharpoons CaO(s) + CO_2(g)}$, which substances appear in the equilibrium constant expression?

Accepted Answer

Only $\mathrm{CO_2}$

Question 10

Consider the following equilibrium: $\mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)}$ with $\Delta H > 0$. What will happen if the temperature is increased?

Accepted Answer

The equilibrium will shift to the right, favoring $\mathrm{NO_2}$.

Question 11

If the equilibrium constant $K$ for a reaction is much greater than 1, what does this indicate about the reaction at equilibrium?

Accepted Answer

Products are favored at equilibrium.

Question 12

For the gaseous reaction $\mathrm{A_2(g) + B_2(g) \rightleftharpoons 2AB(g)}$, how does the equilibrium shift if the total pressure is increased by decreasing the volume?

Accepted Answer

Shifts toward the side with fewer moles of gas.

Question 13

Which of the following is TRUE regarding the relationship between $K_p$ and $K_c$ for a gaseous reaction?

Accepted Answer

$K_p = K_c(RT)^{\Delta n}$, where $\Delta n$ is the change in moles of gas.

Question 14

A system at equilibrium is disturbed by adding more product. According to Le Chatelier’s Principle, what will happen?

Accepted Answer

The system will shift to produce more reactant.

Question 15

Which of the following best describes a homogeneous equilibrium?

Accepted Answer

All reactants and products are in the same phase.

Question 16

In the Haber process ($\mathrm{N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}$), which change would increase the yield of ammonia at equilibrium?

Accepted Answer

Increasing the pressure.

Question 17

For the reaction $\mathrm{2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)}$, what is the effect of removing $\mathrm{O_2}$ from the system at equilibrium?

Accepted Answer

The equilibrium shifts to the left, forming more $\mathrm{SO_2}$ and $\mathrm{O_2}$.

Question 18

Which of the following is NOT included in the equilibrium constant expression for a heterogeneous equilibrium?

Accepted Answer

Pure solids

Question 19

A reaction has $K = 1.2 	imes 10^{-5}$ at a certain temperature. What does this tell you about the equilibrium mixture?

Accepted Answer

The mixture contains mostly reactants.

Question 20

If two reactions are added together, how is the equilibrium constant for the overall reaction related to the equilibrium constants of the individual reactions?

Accepted Answer

It is the product of the individual equilibrium constants.

Chemical Equilibrium: Principles, Expressions, and Applications

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