Question 1

Which of the following statements best describes the difference between a Bronsted-Lowry acid and a Lewis acid?

Accepted Answer

A Bronsted-Lowry acid donates a proton, while a Lewis acid accepts an electron pair.

Question 2

Which of the following aqueous solutions will be basic? Assume all solutions are 0.1 M.

Accepted Answer

Sodium acetate, $$\mathrm{CH_3COONa}$$

Question 3

Which of the following best explains why the percent dissociation of a weak acid increases as its concentration decreases?

Accepted Answer

As the acid is diluted, the equilibrium shifts to produce more ions to counteract the decrease in concentration, increasing percent dissociation.

Question 4

Given the following reaction: $$\mathrm{NH_3$} + \mathrm{H_2O} \rightleftharpoons \mathrm{NH_4$^+} + \mathrm{OH^-}$$, identify the conjugate acid-base pairs.

Accepted Answer

$$\mathrm{NH_3$/NH_4$^+}$$ and $$\mathrm{H_2O/OH^-}$$

Question 5

Which of the following factors increases the strength of a binary acid (HX) as you move down a group in the periodic table?

Accepted Answer

Decreasing bond strength between H and X

Question 6

A 0.10 M solution of a weak acid, HA, has a $$[\mathrm{H_3O^+}] of$$ $$1.3 	imes 10$$^{-3}$$ M. What is the acid dissociation constant, K_a$, for HA?

Accepted Answer

$$K_a = \dfrac{[\mathrm{H_3O^+}]^2}{[HA] - [\mathrm{H_3O^+}]} = \dfrac{(1.3 	imes 10$$^{-3}$$)^2$$}{0.10 - 1.3 	imes $$10^{-3}$$} \approx 1.7 	imes $$10^{-5}$

Question 7

Which of the following best describes the 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 8

Which of the following salts will produce an acidic solution when dissolved in water?

Accepted Answer

Ammonium nitrate, $$\mathrm{NH_4NO_3}$$

Question 9

Which of the following is true regarding the autoionization of water?

Accepted Answer

$$2\mathrm{H_2O} \rightleftharpoons \mathrm{H_3O^+} + \mathrm{OH^-}$$ and $$K_w = [\mathrm{H_3O^+}][\mathrm{OH^-}]$$

Question 10

Which of the following statements is correct regarding polyprotic acids?

Accepted Answer

The first dissociation step provides the majority of $$[\mathrm{H_3O^+}] in $$solution.

Question 11

Which of the following best explains why a reaction between a strong acid and a strong base produces a neutral solution?

Accepted Answer

The resulting salt consists of ions that do not hydrolyze in water, so the solution remains neutral.

Question 12

Which of the following is a Lewis base in the reaction $$\mathrm{NH_3$} + \mathrm{BF_3$} \rightarrow \mathrm{F_3B-NH_3$}$$?

Accepted Answer

$$\mathrm{NH_3$}$$

Question 13

A solution contains $$[\mathrm{HA}] = 0.20 M $$and $$[\mathrm{A^-}] = 0.05 M. Is $$the solution acidic, basic, or neutral? Justify your answer.

Accepted Answer

Acidic, because $$[\mathrm{HA}] \u003e [\mathrm{A^-}] so $$there is more acid than base.

Question 14

Which of the following best describes the behavior of ammonia ($$\mathrm{NH_3$}) in $$water?

Accepted Answer

$$\mathrm{NH_3$}$$ acts as a weak base, accepting a proton from water to form $$\mathrm{NH_4$^+}$$ and $$\mathrm{OH^-}.$$

Question 15

Which of the following combinations will result in a basic solution after mixing equal volumes of 0.1 M solutions?

Accepted Answer

Acetic acid ($$\mathrm{CH_3COOH}) $$and sodium hydroxide ($$\mathrm{NaOH})$$

Question 16

Which of the following statements is true regarding the effect of electronegativity on the strength of oxoacids (e.g., $$\mathrm{HOCl}$$, $$\mathrm{HOBr}$$, $$\mathrm{HOI}$$)?

Accepted Answer

The greater the electronegativity of the central atom, the stronger the acid.

Question 17

A solution is prepared by dissolving 0.10 mol of acetic acid ($$\mathrm{CH_3COOH}) $$and 0.10 mol of sodium acetate ($$\mathrm{CH_3COONa}) in $$enough water to make 1.0 L of solution. What is the pH of the solution if $$K_a = 1.8 	imes 10$$^{-5}$$?

Accepted Answer

$$\mathrm{pH} = pK_a + \log \left( \dfrac{[\mathrm{A^-}]}{[\mathrm{HA}]} ight) = -\log(1.8 	imes 10$$^{-5}$$) + \log(1) = 4.74$$

Question 18

Which of the following best describes the amphiprotic nature of water?

Accepted Answer

Water can act as both a Bronsted-Lowry acid and a Bronsted-Lowry base.

Question 19

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

Accepted Answer

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

Chapter 17 Acid-Base Study Guide: Step-by-Step Guidance

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