A LevelChemistryCambridge (CIE)Exam Questions7. EquilibriaBrønsted–Lowry Theory of Acids & Bases

Brønsted–Lowry Theory of Acids & Bases (Cambridge (CIE) A Level Chemistry): Exam Questions

Exam code: 9701

1 hour17 questions

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Brønsted–Lowry Theory of Acids & Bases

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1
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1 mark

The graph shows the change in pH during a titration.

Which acid and base are used?

pH curve showing pH starting high and decreasing, with equivalence point above pH 7

  • strong acid – strong base

  • strong acid – weak base

  • weak acid – strong base

  • weak acid – weak base

Choose your answer

2
1 mark

According to the Brønsted–Lowry theory, which term describes ammonia?

  • acid

  • amphoteric

  • base

  • neutral

Choose your answer

3
1 mark

Which two species act as Brønsted–Lowry acids in the following reaction?

H3PO4 (aq) + OH- (aq) ⇌ H2PO4- (aq) + H2O (l)

  • H2PO4- (aq) and H2O (l)

  • H2PO4- (aq) and OH- (aq)

  • H3PO4 (aq) and H2PO4- (aq)

  • H3PO4 (aq) and H2O (l)

Choose your answer

4
1 mark

Which statement describes a Brønsted–Lowry base?

  • a species that accepts a pair of electrons to form a dative bond

  • a species that accepts a proton (H+)

  • a species that donates a proton (H+)

  • a species that releases OH- ions in aqueous solution

Choose your answer

1
1 mark

The table shows the concentrations and pH values of two compounds, P and Q, dissolved in water.

solution

concentration / mol dm-3

pH

P

2.0

9.0

Q

2.0

6.0

Which statement is correct?

  • P is a strong base.

  • Q is a strong acid.

  • The extent of dissociation is lower in Q than in P.

  • The extent of dissociation is the same in P and Q.

Choose your answer

2
1 mark

The pH ranges of four indicators are shown.

indicator

pH range for colour change

Bromothymol blue

6.0 – 7.6

Methyl orange

3.2 – 4.4

Phenolphthalein

8.2 – 10.0

Thymol blue

1.2 – 2.8

Which indicator is suitable for a titration of aqueous ammonia with hydrochloric acid?

  • Bromothymol blue

  • Methyl orange

  • Phenolphthalein

  • Thymol blue

Choose your answer

3
1 mark

The following reaction occurs between concentrated sulfuric and nitric acids.

H2SO4 + HNO3 ⇌ H2NO3+ + HSO4-

Which two species act as Brønsted–Lowry bases in this reaction?

  • H2SO4 and H2NO3+

  • H2SO4 and HSO4-

  • HNO3 and H2NO3+

  • HNO3 and HSO4-

Choose your answer

1
1 mark

An equilibrium is established in a mixture of concentrated sulfuric acid and concentrated nitric acid.

H2SO4 + HNO3 ⇌ HSO4- + H2NO3+

Which row describes the behaviour of each species in this equilibrium?

H2SO4

HNO3

HSO4–

H2NO3+

A

acid

acid

base

base

B

base

acid

acid

base

C

acid

base

base

acid

D

acid

base

acid

base

    Choose your answer

    2
    1 mark

    Which two species act as Brønsted–Lowry acids in this reaction?

    H2PO4- (aq) + CN- (aq) ⇌ HCN (aq) + HPO42- (aq)

    • CN- and HPO42-

    • H2PO4- and HCN

    • H2PO4- and HPO42-

    • HCN and CN-

    Choose your answer

    3
    1 mark

    Which statement about 0.01 mol dm-3 CH3COOH (aq) is not correct?

    • the pH = 2

    • [H+] << 0.01 mol dm-3

    • [CH3COO-] is approximately equal to [H+]

    • CH3COOH is partially dissociated

    Choose your answer