Acid Base Equilibria Review

Which acid below has the WEAKEST conjugate base?

• Hydrofluoric acid, HF

  (K_a = 7.2 x 10⁻⁴)

• Acetic Acid, CH₃COOH

  (K_a = 1.8 x 10⁻⁵)

• Hydrocyanic acid, HCN

  (K_a = 6.2 x 10⁻¹⁰)

• Formic acid, HCOOH

  (K_a = 1.8 x 10 ⁻⁴)

Ammonia (NH₃) is a __________.

• weak base

• strong acid

• strong base

• weak acid

Kw = [H₃O⁺] [OH⁻] = 1.0 x 10⁻¹⁴ at 25°C Based on this information, which of the following is true for a sample of pure water at 25°C?

• [H₃O⁺] = 7.0 M

• [OH⁻] = 1.0 x 10⁻¹⁴ M

• pH = 10⁻⁷

• pOH = 7.00

The K_a of hypochlorous acid (HClO) is 3.0 x 10⁻⁸. What is the pH at 25°C of an aqueous solution that is 0.020 M in HClO?

• 7.00

• 2.45

• 4.61

• 9.22

Which one of the following is the weakest acid?

• HF (Ka = 6.8 x 10⁻⁴)

• HC₂H₃O₂ (Ka = 1.8 x 10⁻⁵)

• HNO₂ (Ka = 4.5 x 10⁻⁴)

• HClO (Ka = 3.0 x 10⁻⁸)

Sodium hydroxide is a strong base. This means that __________.

• aqueous solutions of NaOH contain equal concentrations of H⁺ (aq) and OH⁻ (aq)

• NaOH does not dissociate at all when it is dissolved in water

• NaOH dissociates completely to Na⁺(aq) and OH⁻(aq) when it dissolves in water

• NaOH cannot be neutralized by any strong or weak acid

What is the pH of a 0.015-M aqueous solution of barium hydroxide?

• 12.48

• 1.52

• 12.18

• 1.82

Which solution below has the highest concentration of hydroxide ions?

• pH = 3.21

• pH = 9.82

• pH = 7.93

• pH = 12.59

In which of the following aqueous solutions does the weak acid exhibit the highest percent ionization?

• .01 M HC₂H₃O₂

  (K_a 1.8 x 10^-5)

• .01 M HNO₂

  (K_a =4.5 x 10^-4)

• .01 M HClO

  (K_a= 3.0 x 10^-8)

• .01 M HF

  (K_a = 6.8 x 10^-4)

HA is a weak acid. Which equilibrium reaction corresponds to the equilibrium constant K_b for A^-?

• HA _(aq) + H₂O _(l) ⇌ H₂A^+ _(aq) + OH^-_(aq)

• A^- _(aq) + H₃O⁺ _(aq) ⇌ HA _(aq) + H_2O _(l)

• HA _(aq) + OH^- _(aq) ⇌ H₂O _(l) + H^+ _(aq)

• A^- _(aq) + H₂O _(l) ⇌ HA _(aq) + OH^- _(aq)

• A^- _(aq) + OH^- _(aq) ⇌ HOA^2- _(aq)