pH of acids

The K_a of hydrofluoric acid (HF) at 25.0°C is 6.8 x 10^-4. What is the pH of a 0.35 M aqueous solution of HF?

• 3.25

• 1.81

• 3.64

• 1.22

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

• 0.01 M HC₂H₃O₂    (K_a = 1.8 x 10^-5)

• 0.01 M HNO₂    (K_a = 4.5 x 10^-4)

• 0.01 M HF    (K_a = 6.8 x 10^-4)

• 0.01 M HClO    (K_a = 3.0 x 10^-8)

What is the concentration (in M) of hydroxide ions in a solution at 25.0 °C with pH = 4.282?

• 9.72

• 1.91 x 10^-10

• 5.22 x 10^-5

• 1.66 x 10⁴

In basic solution, __________.

• [H₃O⁺] = [OH^-]

• [H₃O⁺] > [OH^-]

• [H₃O⁺] < [OH^-]

• [H₃O⁺] = 0 M

A substance that is capable of acting as both an acid and as a base is __________.

• autosomal

• conjugated

• saturated

• amphoteric

The pH of a 0.10 M solution of a weak base is 9.82. What is the K_b for this base?

• 2.1 x 10^-4

• 4.4 x 10^-8

• 8.8 x 10^-8

• 6.6 x 10^-4

What is the pH of an aqueous solution at 25.0 °C in which [OH^-] is 0.0025 M?

• 11.4

• 2.60

• 2.25

• 11.75

HZ is a weak acid. An aqueous solution of HZ is prepared by dissolving 0.020 mol of HZ in sufficient water to yield 1.0 L of solution. The pH of the solution was 4.93 at 25.0°C. The K_a of HZ is

• 1.2 x10^-5

• 9.9 x 10^-2

• 1.4 x 10^-10

• 6.9 x 10^-9

The K_a of hypochlorous acid (HClO) is 3.0 x 10^-8 at 25.0°C. Calculate the pH of a 0.0385 M hypochlorous acid solution.

• 1.41

• 8.94

• 4.47

• 7.52

Nitric acid is a strong acid.  This means that __________.

• aqueous solutions of HNO₃ contain equal concentrations of H⁺(aq) and OH^-(aq)

• HNO₃ does not dissociate at all when it is dissolved in water

• HNO₃ dissociates completely to H⁺(aq) and NO₃^-(aq) when it dissolves in water

• HNO₃ cannot be neutralized by a weak base