Physical Chemistry 2: Acids, Bases and Buffers Multiple Choice Questions

1. Which of the following mixtures would act as a buffer?

50 cm³ of 0.200 mol dm^-3 HCOOH and 50 cm³ of 0.600 mol dm^-3 NaOH

50 cm³ of 0.600 mol dm^-3 HCOOH and 50 cm³ of 0.200 mol dm^-3 NaOH

50 cm³ of 0.200 mol dm^-3 HCl and 50 cm³ of 0.600 mol dm^-3 NaOH

50 cm³ of 0.200 mol dm^-3 HCl and 50 cm³ of 0.600 mol dm^-3 CH₃COONa

Correct! Wrong!

2. What happens to the Kw and pH of pure water when it is heated?

The Kw decreases and the pH decreases

The Kw decreases and the pH increases

The Kw increases and the pH decreases

The Kw increases and the pH increases

Correct! Wrong!

3. Which of the following acids has the lowest pH?

HCN (Ka = 6.2 x 10^-10 mol dm^-3)

H₂S (Ka = 1.1 x 10^-7 mol dm^-3)

CH₃COOH (Ka = 1.8 x 10^-5 mol dm^-3)

C₆H₅COOH (Ka = 6.3 x 10^-5 mol dm^-3)

Correct! Wrong!

4. At 30℃ the pH of pure water is 6.92. What is the Kw of pure water at this temperature?

1.45 x 10^-14 mol² dm^-6

1.00 x 10^-14 mol² dm^-6

1.20 x 10^-7mol² dm^-6

6.92 x 10¹³ mol² dm^-3

Correct! Wrong!

5. Which of the following statements is NOT correct?

For monobasic strong acids [H⁺] = [OH<sup-]

Weak acids do not fully dissociate in aqueous solution

A Bronsted-Lowry base is a proton acceptor

pKa = -log Ka

Correct! Wrong!

6. 0.300 moles of an acid HX dissociated to give 0.00450 moles of H+.

What is the % dissociation of the acid?

66.7%

1.5%

0.015%

0.667%

Correct! Wrong!

7. What is the pH of a solution of H2SO4 with a concentration of 0.200 mol dm^-3?

0.70

0.63

0.40

0.38

Correct! Wrong!

8. What is the pH of the solution that is formed when 90 cm³ of distilled water is added to 10cm³ of 0.5 mol dm^-3 HCl?

1.30

2.30

0.30

0.22

Correct! Wrong!

9. Which of the following compounds is NOT a Bronsted-Lowry acid?

C₆H₅OH

HF

NH₃

H₃O⁺

Correct! Wrong!

10. In a titration with NaOH the half-neutralisation point of a weak acid was found to be 3.86. What is the Ka of the acid?

3.86

1.38 x 10^-4 mol dm^-3

3.50

2.30 x 10^-5 mol dm^-3

Correct! Wrong!

Gemma Shearer