Acids and bases (2)

For each question choose the answer you consider to be the best.

1. In which reaction is HSO₄^–(aq) acting as a Brønsted - Lowry base?

A. HSO₄^–(aq) + NH₃(aq) → SO₄^2–(aq) + NH₄⁺(aq)

B. HSO₄^–(aq) + OH^–(aq) → SO₄^2–(aq) + H₂O(l)

C HSO₄^–(aq) + CH₃COOH(aq) → H₂SO₄(aq) + CH₃COO^–(aq)

D. HSO₄^–(aq) + CH₃NH₂(aq) → SO₄^2–(aq) + CH₃NH₃⁺(aq)

2. Which species act as Brønsted - Lowry bases in the reaction between nitric acid and sulfuric acid?

HNO₃ + H₂SO₄ ⇌ H₂NO₃⁺ + HSO₄^–

A. HNO₃ + H₂SO₄

B. H₂SO₄ + H₂NO₃⁺

C. HNO₃ + HSO₄^–

D. H₂NO₃⁺ + HSO₄^–

3. Which are the correct definitions of a base according to both Lewis and Brønsted - Lowry theories?

4. Which substance will not react with hydrochloric acid to form a salt?

A. Ag

B. Zn

C. CuCO₃

D. Ca(OH)₂

5. Which list contains only strong bases?

A. Ba(OH)₂, CH₃NH₂, KOH

B. NH₃, KOH, NaOH

C. Ba(OH)₂, KOH, NaOH

D. NaOH, CH₃NH₂, NH3

6. Which statements are correct for equal volumes of solutions of carbonic acid, H₂CO₃(aq), and hydrochloric acid, HCl(aq) with the same concentration?

I. HCl is more dissociated than H₂CO₃.

II. HCl will have a higher pH than H₂CO₃.

III. HCl will be a better electrical conductor than H₂CO₃.

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

7. Separate 1.0 mol dm^-3 solutions of hydrochloric acid and ethanoic acid reacted completely with 10.0 g of calcium carbonate to give carbon dioxide. Which is a correct statement?

A. Both acids also gave hydrogen as a product.

B. The hydrochloric acid solution reacted faster as it has a higher pH.

C. The ethanoic acid solution gave a larger amount of gas.

D. Both solutions produced an equal amount of gas.

8. What is the correct order of increasing pH value for 1.0 mol dm^-3 solutions of the four substances?

A. HCl < CH₃COOH < NH₃ < KOH

B. CH₃COOH < HCl < KOH < NH₃

C. KOH < NH₃ < CH₃COOH < HCl

D. NH₃ < KOH < HCl < CH₃COOH

9. Which compound will produce a solution with a pH greater than 7 when dissolved in water?

A. NaCl

B. NaHSO₄

C. Na₂O

D. NaNO₃

10. The pH of solution A is 1 and the pH of solution B is 2. Which is a correct statement?

A. [H⁺(aq)] in A is ten times that in B.

B. [H⁺(aq)] in B is ten times that in A.

C. [H⁺(aq)] in A is twice that in B.

D. [H⁺(aq)] in A is half that in B.

11. What is the pH of a 0.01 mol dm^-3 solution of ethanoic acid?

A. 2

B. More than 2 but less than 7

C. More than 7 but less than 12

D. 12

12. K_w has a value of 1.0 x 10^-14 at 298 K.
What can be deduced from the fact that at 353 K the value of K_w is 2.0 x 10^-13?

A. Water becomes acidic at higher temperatures.

B. The enthalpy change for the ionization of water is exothermic.

C. The conductivity of water is lower at 353 K than at 298 K.

D. The hydroxide concentration is higher at 353 K than it is at 298 K

13. What is the correct order of increasing acid strength for the following four acids whose pK_a values are given?

P 4.83

Q 4.76

R 4.87

S 4.80

A. P, Q, R, S

B. Q, S, P, R,

C. R, S, P, Q

D. R, P, S, Q

14. What is the pH of a 0.010 mol dm^-3 solution of a weak acid which has an acid dissociation constant, K_a, with a value of 1.0 x 10^-6?

A. 2

B. 3

C. 4

D. 6

15. Which is the weakest?

A. An acid with a pK_a of 5

B. An acid with a K_a value of 2.0 x 10^-5

C. An acid with a K_a value of 2.0 x 10^-6

D. An acid with a pK_a value of 6

16. Methylamine is a weak base in aqueous solution with an ionization constant, K_b. What is the correct expression for the ionization constant for the reaction below?

CH₃NH₃⁺(aq) + H₂O(l) ⇌ CH₃NH₂(aq) + H₃O⁺(aq)

A. K_w x K_b

B. K_w / K_b

C. K_w x K_a

D. K_w / K_a

17. Which pair of solutions could be used to prepare a buffer solution?

A. CH₃COOK(aq) + KOH(aq)

B. CH₃NH₂(aq) + CH₃NH₃NO₃(aq)

C. CH₃COOH(aq) + CH₃NH₂(aq)

D. CH₃NH₃NO₃ + HNO₃

18. What is the pH of a buffer solution in which the concentration of methanoic acid (K_a = 1.8 x 10^-4) is 1.0 mol dm^-3 and the concentration of sodium methanoate is 2.0 mol dm^-3?

A. Between 2 and 3

B. Between 3 and 4

C. Between 4 and 5

D. Between 5 and 6

19. What is the pH of acid rain?

A. Less than 5.6

B. 5.6

C. More than 5.6

D. More than 5.6 but less than 7.0

20. Which statement about the acid-base indicator HIn is correct?

A. In strongly alkaline solution the indicator will be blue.

B. At very low pH values the indicator will be blue.

C. At pH = 7 the indicator will be green.

D. At very high pH values the indicator will be yellow.

Answers

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