Question 1

Which statement best describes dynamic equilibrium in a chemical reaction?

Accepted Answer

The rates of the forward and reverse reactions are equal, and concentrations remain constant over time.

Question 2

For the reaction $$2CH_4(g) \rightleftharpoons C_2H_2(g) + 3H_2(g)$$, which is the correct equilibrium constant expression?

Accepted Answer

$$K = \frac{[C_2H_2][H_2$]^3}{[CH_4$]^2}$$

Question 3

A reaction mixture initially contains $$[CO] = 0.80\,M$$ and $$[H_2$] = 2.00\,M. At $$equilibrium, $$[H_2$] = 0.60\,M. $$What is the equilibrium concentration of $$CH_3OH$$ for the reaction $$CO(g) + 2H_2(g) \rightleftharpoons CH_3OH(g)$$?

Accepted Answer

$$0.70\,M$$

Question 4

Which of the following changes will NOT affect the position of equilibrium for a gas-phase reaction at constant volume?

Accepted Answer

Adding an inert gas

Question 5

For the reaction $$N_2O_5(g) \rightleftharpoons 4NO_2(g) + O_2$(g)$$, what is the correct equilibrium constant expression?

Accepted Answer

$$K = \frac{[NO_2$]^4[O_2$]}{[N_2O_5]}$$

Question 6

If the equilibrium constant $$K$$ for a reaction is much greater than 1, which statement is true?

Accepted Answer

The reaction favors the formation of products at equilibrium.

Question 7

For the reaction $$2NO_2(g) \rightleftharpoons N_2O_4(g)$$, $$K = 0.36 at$$ $$100^	ext{o}C. If a $$mixture initially contains $$[NO_2$] = 0.100\,M$$, what is the equilibrium concentration of $$N_2O_4$$?

Accepted Answer

$$0.014\,M$$

Question 8

Which of the following is true about the equilibrium constant $$K$$?

Accepted Answer

It is constant at a given temperature, regardless of initial concentrations.

Question 9

For the reaction $$A(g) + 2B(g) \rightleftharpoons \frac{1}{2}C(g)$$, $$K = 0.03. $$What is the equilibrium constant for the reaction $$C(g) \rightleftharpoons 2A(g) + 4B(g)$$?

Accepted Answer

$$K = \frac{1}{(0.03)^2$}$$

Question 10

Which of the following is NOT included in the equilibrium constant expression for the reaction $$CO_2(g) + H_2O(l$$) \rightleftharpoons H^+(aq) + $$HCO_3^-(aq$$)$$?

Accepted Answer

$$[H_2O]$$

Question 11

If the reaction $$H_2(g$$) + $$I_2(g$$) \rightleftharpoons 2HI(g)$$ has K_c = 620$ at 25^	$$ext{o}C$$, what is the value of K_c$ for the reverse reaction 2HI(g$$) \rightleftharpoons $$H_2(g$$) + $$I_2(g$$)$$?

Accepted Answer

$$K_c = \frac{1}{620}$$

Question 12

Which of the following will cause the equilibrium position of an exothermic reaction to shift to the left?

Accepted Answer

Increasing the temperature

Question 13

For the reaction $$aA(g) + bB(g) \rightleftharpoons cC(g) + dD(g)$$, the equilibrium constant in terms of partial pressures is given by:

Accepted Answer

$$K_p = \frac{P_C^c P_D^d}{P_A^a P_B^b}$$

Question 14

A catalyst is added to a reaction mixture at equilibrium. What effect does this have?

Accepted Answer

It increases the rate at which equilibrium is reached, but does not change the position of equilibrium.

Question 15

If $$Q \u003c K$$ for a reaction mixture, what will happen?

Accepted Answer

The reaction will proceed in the forward direction to reach equilibrium.

Question 16

Which of the following best describes the effect of decreasing the volume of a reaction vessel for the reaction $$CaO(s) + CO_2$(g) \rightleftharpoons $$CaCO_3$$(s)$$?

Accepted Answer

The equilibrium shifts to the right, favoring $$CaCO_3(s$$)$$ formation.

Question 17

For the reaction $$Hb + O_2$ \rightleftharpoons $$HbO_2$$, what is the physiological significance of this equilibrium?

Accepted Answer

It enables hemoglobin to reversibly bind and release oxygen, enhancing oxygen transport in the blood.

Question 18

Which of the following will cause the equilibrium position of an endothermic reaction to shift to the right?

Accepted Answer

Increasing the temperature

Question 19

For the reaction $$2BrNO(g) \rightleftharpoons 2NO(g) + Br_2$(g)$$, what is the effect of removing some $$BrNO(g)$$ from the reaction mixture?

Accepted Answer

Reaction shifts left.

Chemical Equilibrium: Principles, Constants, and Applications

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