Question 1

Which of the following best describes dynamic equilibrium in a chemical reaction?

Accepted Answer

The rate of the forward reaction equals the rate of the reverse reaction, and the concentrations of reactants and products remain constant.

Question 2

For the reaction $$2NO(g) + O_2$(g) ightleftharpoons 2NO_2(g)$$, the equilibrium constant $$K_c is$$ $$2.2 	imes 10$$^{12}$$ at 25$$^\circ$$C. What does this value indicate about the position of equilibrium?

Accepted Answer

The reaction strongly favors the formation of products.

Question 3

If the equilibrium constant $$K$$ for a reaction is much less than 1, what can be inferred about the reaction at equilibrium?

Accepted Answer

There are more reactants than products.

Question 4

Which of the following changes will shift the equilibrium of $$N_2(g) + 3H_2(g$$) \rightleftharpoons 2NH_3(g)$$ to the right according to Le Chatelier's Principle?

Accepted Answer

Decreasing the volume of the container

Question 5

For the reaction $$2SO_2(g) + O_2$(g) \rightleftharpoons 2SO_3(g)$$, what happens to the equilibrium if the volume of the reaction vessel is decreased?

Accepted Answer

The reaction shifts toward the side with fewer moles of gas.

Question 6

Which of these cartoons depicts the most concentrated weak acid? (Refer to the first image provided)

Accepted Answer

D

Question 7

What is the correct equilibrium constant expression for the reaction $$aA + bB \rightleftharpoons cC + dD$$?

Accepted Answer

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

Question 8

A buffer solution is created using $$0.15 M$$ $$HC_2H_3O_2$$ and $$0.10 M$$ $$NaC_2H_3O_2. $$What is the pH of the buffer if $$pK_a = 4.76$$?

Accepted Answer

$$pH = 4.76 + \log\left(\frac{0.10}{0.15}\right)$$

Question 9

Which of the following mixtures would NOT function well as a buffer? (Refer to the list in image 10)

Accepted Answer

0.10 M HCl & 0.10 M NaCl

Question 10

Which acid has the lowest p$$K_a$$ value and is therefore the strongest acid among the following: $$CH_3COOH$$, $$H_2CO_3$$, $$H_3PO_4$$? (Refer to image 14)

Accepted Answer

$$H_3PO_4$$

Question 11

A weak acid solution has a concentration of $$0.078 M $$and is $$3.5\%$$ ionized. What is the concentration of $$H^+$$ ions?

Accepted Answer

$$0.00273 M$$

Question 12

Which of the following statements about entropy ($$S) is $$correct?

Accepted Answer

Entropy increases when a solid melts.

Question 13

For the dissolution of $$Hg_2$$($$N_3)_2(s$$)$$ in water, which of the following is the correct equilibrium expression for the solubility product (K$$_{sp}$$)?

Accepted Answer

$$K_{sp} = [Hg_2$^{2+}] [N_3$^-]^2$$

Question 14

Which of the following is true about the relationship between $$K_c$$ and $$K_p$$ for a gaseous reaction where the number of moles of gas does not change?

Accepted Answer

$$K_p = K_c$$

Question 15

Which of the following best describes a Bronsted-Lowry acid?

Accepted Answer

A substance that donates a proton ($$H^+).$$

Question 16

If the temperature of an exothermic reaction at equilibrium is increased, what happens to the equilibrium constant $$K$$?

Accepted Answer

$$K$$ decreases

Question 17

Which equation is used to relate the pH of a buffer solution to the concentrations of acid and conjugate base?

Accepted Answer

$$pH = pK_a + \log\left(\frac{[A^-]}{[HA]}\right)$$

Question 18

Which of the following is a correct statement about the effect of a catalyst on a reaction at equilibrium?

Accepted Answer

A catalyst does not affect the position of equilibrium.

Acids, Bases, and Buffer Systems: Equilibrium and pH in Aqueous Solutions

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