SCH4U8
Acid-Base Equilibrium worksheet
1.Formic acid, HCOOH, is present in the sting of certain ants. What is the pH of a 0.025 mol/L
solution? (A: 2.70)
2.Calculate the pH of a sample of vinegar that contains 0.83 mol/L acetic acid. What is the
percent dissociation of the vinegar? (A:2.41, 0.46 %)
3.The formula of barbituric acid is C4H4N2O3. A chemist prepares a 0.10 M solution and finds
the pH to be 2.50. What is the acid dissociation constant for barbituric acid? What percent of its
molecules dissociate? (A: 1.0 x10-4, 3.2 %)
4.A solution of hydrofluoric acid has a molar concentration of 0.0100 mol/L. What is the pH of
this solution? (A: 2.65)
5.Hypochlorous acid, HOCl, is used as a bleach and a germ-killer. A chemist finds that 0.027 %
of hypochlorous acid molecules are dissociated in a 0.40 mol/L solution of the acid. What is the
value of Ka for the acid? (A: 2.9 x 10-8)
6.Butanoic acid gives rancid butter its distinctive odour. Calculate the pH of a 1.0 x 10-2 mol/L
solution of butanoic acid, given that Ka= 1.51 x10-5. (A:3.411)
7.Caproic acid, C5H11COOH, occurs naturally in coconut and palm oil. It is a weak acid with Ka
= 1.3 x10-5. A certain aqueous solution of caproic acid has a pH of 2.94. How much acid was
dissolved to make 100 mL of this solution? (A:1.2 g)
8.Calculate the pH of a solution of 5.0 x10-4 mol/L carbonic acid. What is [CO32-] in the
solution? (A:4.82, 4.7 x10-11 M)
9.Adipic acid is a diprotic acid that is used to manufacture nylon. Its formula can be abbreviated
to H2Ad. The acid dissociation constants for adipic acid are Ka1 = 3.71 x10-5 and
Ka2 = 3.87 x10-6. What is the pH of a 0.085 mol/L solution? (A:2.74)
10.Hydrosulfuric acid is a weak diprotic acid. Calculate the pH and [HS-] of a 7.5 x10-3 M
solution. (A: 4.59, 2.6 x10-5 M)
11.An aqueous solution of household ammonia has a molar concentration of 0.105 M. Calculate
the pH of the solution. (A: 11.14)
12.Hydrazine, N2H4, has been used as a rocket fuel. The concentration of an aqueous solution of
hydrazine is 5.9 x10-2 mol/L. Calculate the pH of the solution. (A: 10.50)
13.Morphine, C17H19NO3, is a naturally occurring base that is used to control pain. A 4.5 x10-3
mol/L solution has a pH of 9.93. Calculate Kb for morphine. (A: 1.6 x10-6)
14.At room temperature, trimethylamine, (CH3)3N, is a gas with a strong ammonia-like odour.
Calculate [OH-] and the percent of trimethylamine molecules that react with water in a 0.22
mol/L aqueous solution. (A: 3.8 x10-3, 1.7 %)
15.An aqueous solution of ammonia has a pH of 10.85. What is the concentration of the
solution? (A: 2.8 x 10-2 mol/L)
16.Sodium benzoate is used as a food preservative. Calculate the pH of a 1.0 mol/L aqueous
solution of sodium benzoate (Ka for benzoic acid is 6.3 x10-5). (A: 9.10)
17.Potassium sorbate is a common additive in foods. It is used to inhibit the formation of mould.
A solution contains 1.82 g of sorbate, C6H7O2-, ions (Ka = 1.7 x10-5) dissolved in 250 mL of
water. What is the pH of the solution? (A: 8.80)
18.Phenol, C6H5OH, is an aromatic alcohol with weak basic properties. Calculate the molar
concentration of OH- ions in a 0.75 M solution of phenolate, C6H5O-, ions (Kb = 7.7 x10-5).
What is the pH of the solution? (A: 7.6 x10-3, 11.88)
19.Calculate the pH of a 0.10 M aqueous solution of sodium nitrite. (A: 8.07)
20.A student prepared a saturated solution of salicylic acid and measured the pH of the solution.
The student then carefully evaporated 100 mL of the solution and collected the solid. If the pH
of the solution was 2.43, and 0.22 g was collected after evaporating 100 mL of the solution, what
is the acid dissociation constant for salicylic acid? (A: 1.1 x10-3)