Question 1

Which of the following best describes the state of chemical equilibrium in a closed system?

Accepted Answer

The rates of the forward and reverse reactions are equal, and the concentrations of reactants and products remain constant.

Question 2

For the reaction $$\mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)}$$, the equilibrium constant expression in terms of concentration ($$K_c) is$$:

Accepted Answer

$$K_c = \frac{[NO_2$]^2}{[N_2O_4]}$$

Question 3

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

Accepted Answer

The reaction favors the products.

Question 4

For the Haber process $$\mathrm{N_2$(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}$$, how would the equilibrium constant $$K$$ change if the equation is reversed?

Accepted Answer

The new $$K is $$the reciprocal of the original $$K.$$

Question 5

A reaction has $$K_c = 0.001. $$Which statement is true about the equilibrium mixture?

Accepted Answer

Reactants predominate at equilibrium.

Question 6

For the reaction $$\mathrm{2SO_2(g) + O_2$(g) \rightleftharpoons 2SO_3(g)}$$, the equilibrium constant in terms of pressure ($$K_p) is$$:

Accepted Answer

$$K_p = \frac{P_{SO_3$}^2}{P_{SO_2$}^2 P_{O_2$}}$$

Question 7

If the equation for a reaction is multiplied by 2, how is the new equilibrium constant ($$K_{new}) $$related to the original equilibrium constant ($$K_{original}$$)?

Accepted Answer

$$K_{new} = K_{original}^2$$

Question 8

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

Accepted Answer

Pure solids

Question 9

A closed system initially contains 1.0 M $$\mathrm{H_2$}$$ and 2.0 M $$\mathrm{I_2$}$$, with no $$\mathrm{HI}. At $$equilibrium, $$[HI] = 1.87 	imes 10$$^{-3}$$ M. What is the change in $$[$$H_2$$]$$?

Accepted Answer

$$-9.35 	imes 10$$^{-4}$$ M

Question 10

Given the reaction $$\mathrm{$$CaCO_3$$(s) \rightleftharpoons CaO(s) + CO_2$(g)}$$, what is the correct equilibrium constant expression?

Accepted Answer

$$K = [CO_2$]$$

Question 11

If the reaction quotient $$Q is $$less than the equilibrium constant $$K$$, what will happen in the system?

Accepted Answer

The reaction will shift toward products.

Question 12

A catalyst is added to a reaction mixture at equilibrium. What is the effect on the equilibrium position and the value of $$K$$?

Accepted Answer

The equilibrium is reached faster, but the equilibrium position and $$K$$ remain unchanged.

Question 13

For the reaction $$\mathrm{A(g) + B(g) \rightleftharpoons 2C(g)}$$, if the volume of the container is increased, what will happen to the equilibrium position?

Accepted Answer

It will shift toward the side with more moles of gas.

Question 14

Which of the following changes will increase the value of the equilibrium constant $$K$$ for an endothermic reaction?

Accepted Answer

Increasing the temperature

Question 15

Two consecutive equilibria are combined to give a single reaction. How is the new equilibrium constant related to the original constants?

Accepted Answer

It is the product of the two constants.

Question 16

A 1.0 L flask contains 1.0 mol $$\mathrm{H_2$}$$ and 2.0 mol $$\mathrm{I_2$}. At $$equilibrium, $$[HI] = 1.87 	imes 10$$^{-3}$$ M. What is the equilibrium constant K_c$ for $$\mathrm{$$H_2(g$$) + $$I_2(g$$) ightleftharpoons 2HI(g)}$$?

Accepted Answer

$$K_c = \frac{(1.87 	imes 10$$^{-3}$$)^2$$}{(6.5 	imes $$10^{-5})(1.065$$ 	imes $$10^{-3}$$)}$

Question 17

Which of the following statements about Le Châtelier’s Principle is correct?

Accepted Answer

Removing a product will shift the equilibrium toward the products.

Question 18

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

Accepted Answer

It shifts toward the side with fewer moles of gas.

Chemical Equilibrium: Principles and Calculations

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