Question 1

For the equilibrium reaction $\mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)}$, what will happen to the equilibrium position if more $\mathrm{NO_2(g)}$ is added to the system?

Accepted Answer

The equilibrium will shift to the left, favoring the formation of $\mathrm{N_2O_4(g)}$.

Question 2

Consider the reaction $\mathrm{CaCO_3(s) \rightleftharpoons CaO(s) + CO_2(g)}$. What effect does adding more $\mathrm{CaO(s)}$ have on the equilibrium?

Accepted Answer

No change; the equilibrium position remains the same.

Question 3

For the reaction $\mathrm{N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}$, what happens to the equilibrium if the volume of the container is decreased at constant temperature?

Accepted Answer

The equilibrium shifts to the right, favoring $\mathrm{NH_3(g)}$ formation.

Question 4

Which of the following changes will increase the partial pressure of $\mathrm{N_2O_4(g)}$ in the equilibrium $\mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)}$?

Accepted Answer

Add more $\mathrm{NO_2(g)}$ and compress the container.

Question 5

For the exothermic reaction $\mathrm{A + B \rightleftharpoons C + D + heat}$, what is the effect of increasing the temperature?

Accepted Answer

The equilibrium shifts to the left, favoring reactants.

Question 6

Given the reaction $\mathrm{CO(g) + 3H_2(g) \rightleftharpoons CH_4(g) + H_2O(g)}$ with $\Delta H = -206.2\ \mathrm{kJ\ mol^{-1}}$, how does the equilibrium constant $K$ change as temperature increases?

Accepted Answer

The equilibrium constant $K$ decreases.

Question 7

For the endothermic reaction $\mathrm{N_2O_4(g) + heat \rightleftharpoons 2NO_2(g)}$, what will happen to the equilibrium position if the temperature is increased?

Accepted Answer

The equilibrium shifts to the right, favoring $\mathrm{NO_2(g)}$.

Question 8

If an inert gas is added to a reaction vessel at constant volume, what is the effect on the equilibrium position of a gaseous reaction?

Accepted Answer

No effect; the equilibrium position remains unchanged.

Question 9

For the reaction $\mathrm{N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}$, which of the following will increase the concentration of $\mathrm{NH_3(g)}$ at equilibrium?

Accepted Answer

Increase pressure (decrease volume) and decrease temperature.

Question 10

Which statement best describes Le Chatelier's Principle?

Accepted Answer

If a system at equilibrium is disturbed, it will shift in the direction that counteracts the disturbance.

Question 11

For the equilibrium $\mathrm{N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}$, what is the effect of increasing the volume of the container at constant temperature?

Accepted Answer

The equilibrium shifts to the left, favoring $\mathrm{N_2(g)}$ and $\mathrm{H_2(g)}$.

Question 12

Consider the equilibrium $\mathrm{PCl_5(g) \rightleftharpoons PCl_3(g) + Cl_2(g)}$ with $\Delta H = +89.7\ \mathrm{kJ\ mol^{-1}}$. What is the effect of increasing temperature?

Accepted Answer

The equilibrium shifts to the right, favoring $\mathrm{PCl_3(g)}$ and $\mathrm{Cl_2(g)}$.

Question 13

For the reaction $\mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)}$, what happens if the volume of the container is increased?

Accepted Answer

The equilibrium shifts to the right, favoring $\mathrm{NO_2(g)}$.

Question 14

Which of the following will NOT affect the equilibrium position of a reaction?

Accepted Answer

Adding an inert gas at constant volume.

Question 15

For the reaction $\mathrm{CO(g) + 3H_2(g) \rightleftharpoons CH_4(g) + H_2O(g)}$, which of the following will increase the yield of $\mathrm{CH_4(g)}$?

Accepted Answer

Decrease temperature and increase pressure.

Question 16

A reaction at equilibrium has equal moles of gas on both sides. What is the effect of changing the volume of the container?

Accepted Answer

No effect; the equilibrium position remains unchanged.

Question 17

For the reaction $\mathrm{N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}$, which of the following will decrease the concentration of $\mathrm{NH_3(g)}$ at equilibrium?

Accepted Answer

Increase temperature and increase volume.

Question 18

For the equilibrium $\mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)}$, which of the following will increase the concentration of $\mathrm{NO_2(g)}$?

Accepted Answer

Increase temperature and increase volume.

Chemical Equilibrium and Le Châtelier’s Principle: Effects of Concentration, Volume, and Temperature

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