Reactions of acids

4 marks · Normal

The following questions concern acids and bases.

(a)

Define the term 'base' in terms of proton transfer.

[1 mark]

(b)

Complete the following equation for a reaction between an acid and a base:

[1 mark]

(c)

Explain, in terms of proton transfer, what happens in this reaction.

[2 marks]

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

Show answer

(a) A base is a proton (H+) acceptor.

(b) NaNO3(aq) + H2O(l) · must show NaNO3(aq) + H2O(l)

(c) The acid (HNO3) donates a proton to OH- from NaOH, forming water. The base accepts the proton from the acid. · must show acid donates proton to base, water is formed by transfer of H+ to OH-

Common mistakes: Inverting donor/acceptor roles; incomplete equation.

Show mark scheme and worked solution

Marking points

B1 (a) · 1 mark · Defines base as a proton (H+) acceptor.

B2 (b) · 1 mark · Completes equation: HNO3(aq) + NaOH(aq) -> NaNO3(aq) + H2O(l)

B3 (c) · 1 mark · Explains proton transfer: acid donates proton to base/OH-.

B4 (c) · 1 mark · Mentions water is formed as a result of proton transfer.

Worked solution

a) A base is a proton acceptor.

b) The completed equation:

c) The acid (nitric acid) donates a proton (H+) to the hydroxide ion (OH-) from sodium hydroxide. The base accepts the proton and water is formed.