Q: A reaction mixture initially contains $$0.500\ \mathrm{M}$$ $$\mathrm{CH_3OH}$$ and no $$\mathrm{CO} or$$ $$\mathrm{H_2$}. $$For the reaction $$\mathrm{CH_3OH(g) \rightleftharpoons CO(g) + 2H_2(g)}$$ with $$K = 4.42 \times 10$$^{-7}$$ at 725$$\ \mathrm{K}$$, what is the equilibrium concentration of $$\mathrm{CO}$$? (Assume x$ is small compared to 0.500$.)

$$x = 3.91 \times 10$$^{-4}$$\ \mathrm{M}$$

Question 1

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

Accepted Answer

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

Question 2

Consider the equilibrium $$\mathrm{2SO_2(g) + O_2$(g) \rightleftharpoons 2SO_3(g)}. If $$the volume of the container is decreased at constant temperature, what will be the effect on the equilibrium?

Accepted Answer

The equilibrium will shift to the right, producing more $$\mathrm{SO_3$}.$$

Question 3

For the reaction $$\mathrm{A(g) + B(g) \rightleftharpoons C(g) + D(g)}$$, $$\Delta H \u003e 0. $$What will happen to the equilibrium if the temperature is increased?

Accepted Answer

The equilibrium will shift to the right, favoring the formation of $$\mathrm{C}$$ and $$\mathrm{D}.$$

Question 4

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 5

Given the reaction $$\mathrm{NH_4OCONH_2(s) \rightleftharpoons 2NH_3(g) + CO_2$(g)}$$, what is the correct expression for the reaction quotient $$Q$$?

Accepted Answer

$$Q = [NH_3$]^2[CO_2$]$$

Question 6

A reaction mixture initially contains $$0.500\ \mathrm{M}$$ $$\mathrm{CH_3OH}$$ and no $$\mathrm{CO} or$$ $$\mathrm{H_2$}. $$For the reaction $$\mathrm{CH_3OH(g) ightleftharpoons CO(g) + 2H_2(g)}$$ with $$K = 4.42 	imes 10$$^{-7}$$ at 725$$\ \mathrm{K}$$, what is the equilibrium concentration of $$\mathrm{CO}$$? (Assume x$ is small compared to 0.500$.)

Accepted Answer

$$x = 3.91 	imes 10$$^{-4}$$\ \mathrm{M}$$

Question 7

For the equilibrium $$\mathrm{$$PCl_5$$(g) \rightleftharpoons $$PCl_3$$(g) + Cl_2$(g)}$$ with $$\Delta H = +87.9\ \mathrm{kJ}$$, what will happen if $$\mathrm{Cl_2$} is $$removed from the system?

Accepted Answer

The equilibrium will shift to the right, producing more $$\mathrm{$$PCl_3$$}$$ and $$\mathrm{Cl_2$}.$$

Question 8

Which of the following changes will NOT affect the value of the equilibrium constant $$K$$ for a reaction?

Accepted Answer

Adding a catalyst.

Question 9

For the reaction $$\mathrm{2NO_2(g) \rightleftharpoons N_2O_4(g)}$$, what will happen if the pressure is increased by decreasing the volume?

Accepted Answer

The equilibrium will shift to the right, forming more $$\mathrm{N_2O_4}.$$

Question 10

A system at equilibrium has $$Q \u003c K. $$What will happen to the concentrations of products and reactants as the system moves toward equilibrium?

Accepted Answer

The concentration of products will increase and the concentration of reactants will decrease.

Question 11

Which of the following best describes LeChatelier's Principle?

Accepted Answer

A system at equilibrium will shift to minimize the effect of a disturbance.

Question 12

For the reaction $$\mathrm{C(s) + H_2O(g) \rightleftharpoons CO(g) + H_2$(g)}$$, which of the following changes will shift the equilibrium to the right?

Accepted Answer

Removing $$\mathrm{H_2$}.$$

Question 13

If the reaction $$\mathrm{A(g) \rightleftharpoons 2B(g)} is at $$equilibrium and the volume of the container is doubled, what will happen to the equilibrium position?

Accepted Answer

The equilibrium will shift to the right, producing more $$\mathrm{B}.$$

Question 14

Which of the following is true regarding heterogeneous equilibria?

Accepted Answer

Only species in the gas or aqueous phase appear in the equilibrium expression.

Question 15

For the exothermic reaction $$\mathrm{C_2H_4(g) + H_2$(g) \rightleftharpoons C_2H_6(g)}$$, what will happen if the temperature is decreased?

Accepted Answer

The equilibrium will shift to the right, producing more $$\mathrm{C_2H_6}.$$

LeChatelier’s Principle and Chemical Equilibrium: Effects of Disturbances on Equilibrium Systems

Study Guide - Practice Questions

Study Guide - Flashcards