3.1.12 Acids and bases (A-level only)

In which one of the following reactions is the role of the reagent stated correctly?

• A

• B

• C

• D

The rate equation for the acid-catalysed reaction between iodine and propanone is:

rate = k [H⁺] [C₃H₆O]

The rate of reaction was measured for a mixture of iodine, propanone and sulfuric acid at pH = 0.70

In a second mixture the concentration of the sulfuric acid was different but the concentrations of iodine and propanone were unchanged. The new rate of reaction was a quarter of the original rate.

What was the pH of the second mixture?

• 1.00

• 1.30

• 1.40

• 2.80

What is the pH of a 0.020 mol dm^–3 solution of a diprotic acid which is completely dissociated?

• 1.00

• 1.40

• 1.70

• 4.00

Use the information about the following solutions to answer the question below.

Solution F: This is a mixture of 1 mol of propanoic acid, 1 mol of methanol and 2 mol of water.

Solution G: This was originally the same mixture as solution F but it has been left to reach equilibrium.

Compared to the pH of solution F, the pH of solution G will be

• considerably lower.

• slightly lower.

• slightly higher.

• exactly the same.

This question is about the reaction between propanone and an excess of ethane-1,2-diol, the equation for which is given below.

In a typical procedure, a mixture of 1.00 g of propanone, 5.00 g of ethane-1,2-diol and 0.100 g of benzenesulphonic acid, C₆H₅SO₃H, is heated under reflux in an inert solvent. Benzenesulphonic acid is a strong acid.

If 0.100 g of the strong monoprotic acid, benzenesulphonic acid, was dissolved in 100 cm³ of water, the pH of the solution would be

• 0.20

• 1.20

• 2.20

• 3.20

The equation and rate law for the reaction of substance P with substance Q are given below.

2P + Q → R + S

rate = k[P]²[H⁺]

Under which one of the following conditions, all at the same temperature, would the rate of reaction be slowest?

• [P] / mol dm⁻³: 0.1

  pH: 0

• [P] / mol dm⁻³: 1

  pH: 2

• [P] / mol dm⁻³: 3

  pH: 3

• [P] / mol dm⁻³: 10

  pH: 4

Addition of which one of the following to 10 cm³ of 1.0 M NaOH would result in the pH being halved?

• 10 cm³ of water

• 100 cm³ of water

• 5 cm³ of 1.0 M HCl

• 10 cm³ of 1.0 M HCl

The pH of 0.001 M NaOH at 25°C is

• 13

• 11

• 9

• 3

Which one of the following is the change in units of pH which occurs when 10.0 cm³ of a 1.0 M solution of a strong monoprotic acid are made up to 1.0 dm³ with water?

• 1

• 2

• 3

• 5

What is the pH of a 0.46 mol dm⁻³ solution of potassium hydroxide at 298 K?

(K_w = 1.0 × 10⁻¹⁴ mol² dm⁻⁶ at 298 K)

• 0.34

• 13.66

• 13.96

• 14.34