Q: Which of the following acids would you expect to have the strongest conjugate base?

Hydrocyanic acid ($$\mathrm{HCN}$$, $$K_a = 4.9 \times 10$$^{-10}$$)

Q: A solution has a pH of 3.0. What is the hydronium ion concentration $$[\mathrm{H_3O^+}]$$?

$$1.0 \times 10$$^{-3}$$\ \mathrm{M}$$

Q: A 0.20 M solution of a weak base has a pH of 11.30. What is the $$[\mathrm{OH^-}] in $$the solution?

$$2.0 \times 10$$^{-3}$$\ \mathrm{M}$$

Question 1

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

Accepted Answer

A substance that donates a proton ($$\mathrm{H^+}) to $$another substance.

Question 2

Which of the following statements about the autoionization of water is correct?

Accepted Answer

The product of $$[\mathrm{H_3O^+}]$$ and $$[\mathrm{OH^-}] is $$constant at a given temperature.

Question 3

A 0.10 M solution of acetic acid ($$\mathrm{CH_3COOH}$$, $$K_a = 1.8 	imes 10$$^{-5}$$) is prepared. Which of the following is the correct expression for the acid ionization constant?

Accepted Answer

$$K_a = \dfrac{[\mathrm{CH_3COO^-}][\mathrm{H_3O^+}]}{[\mathrm{CH_3COOH}]}$$

Question 4

Which of the following acids would you expect to have the strongest conjugate base?

Accepted Answer

Hydrocyanic acid ($$\mathrm{HCN}$$, $$K_a = 4.9 	imes 10$$^{-10}$$)

Question 5

A solution has a pH of 3.0. What is the hydronium ion concentration $$[\mathrm{H_3O^+}]$$?

Accepted Answer

$$1.0 	imes 10$$^{-3}$$\ \mathrm{M}$$

Question 6

Which of the following best explains why $$\mathrm{HCl} is a $$stronger acid than $$\mathrm{HF}$$?

Accepted Answer

The H–Cl bond is weaker and more easily broken than the H–F bond.

Question 7

A 0.20 M solution of a weak base has a pH of 11.30. What is the $$[\mathrm{OH^-}] in $$the solution?

Accepted Answer

$$2.0 	imes 10$$^{-3}$$\ \mathrm{M}$$

Question 8

Which of the following is the correct relationship between $$K_a$$, $$K_b$$, and $$K_w$$ for a conjugate acid-base pair?

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 9

A 0.10 M solution of a monoprotic strong acid is prepared. What is the pH of the solution?

Accepted Answer

1.00

Question 10

Which of the following best describes the effect of dilution on the pH of a weak acid solution?

Accepted Answer

The pH increases, but not as much as for a strong acid of the same initial concentration.

Question 11

Which of the following is a correct Lewis acid-base reaction?

Accepted Answer

$$\mathrm{BF_3$} + :\mathrm{NH_3$} \rightarrow \mathrm{F_3B-NH_3$}$$

Question 12

A student mixes 0.10 M $$\mathrm{NH_3$} (a $$weak base) with 0.10 M $$\mathrm{HCl} (a $$strong acid). What is the major species present after the reaction goes to completion?

Accepted Answer

$$\mathrm{NH_4$^+}$$

Question 13

Which of the following statements is true regarding the pH of a 0.10 M solution of $$\mathrm{NaOH}$$?

Accepted Answer

The pH is 13.00.

Question 14

Which of the following best explains why $$\mathrm{H_2SO_4} is a $$strong acid in its first ionization but only moderately strong in its second ionization?

Accepted Answer

The first proton is lost easily due to charge delocalization, but the second proton is removed from a negatively charged ion, making it less favorable.

Question 15

A solution is prepared by dissolving 0.10 mol of $$\mathrm{NaF} in $$enough water to make 1.0 L of solution. Given that $$\mathrm{HF} is a $$weak acid, what is the effect of adding $$\mathrm{NaF} to a $$solution of $$\mathrm{HF}$$?

Accepted Answer

It suppresses the ionization of $$\mathrm{HF}$$ due to the common ion effect.

Question 16

Which of the following is the correct formula for calculating the pOH of a solution?

Accepted Answer

$$\mathrm{pOH} = -\log [\mathrm{OH^-}]$$

Question 17

A 0.10 M solution of a weak acid has a pH of 3.0. What is the percent ionization of the acid?

Accepted Answer

1.0\%

Question 18

Which of the following best describes the relationship between acid strength and the stability of its conjugate base?

Accepted Answer

The stronger the acid, the more stable its conjugate base.

Question 19

A patient is suffering from metabolic alkalosis, which means their blood pH is above normal. Which of the following would help return their blood pH to normal?

Accepted Answer

Administering a weak acid to neutralize excess base.

Question 20

Which of the following is the correct expression for the $$K_b of $$ammonia ($$\mathrm{NH_3$}) in $$water?

Accepted Answer

$$K_b = \dfrac{[\mathrm{NH_4$^+}][\mathrm{OH^-}]}{[\mathrm{NH_3$}]}$$

Acids and Bases: Concepts, Strength, and Calculations

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