Displacement reactions involving solutions of salts

4 marks · Normal

Aluminium reacts with a solution of copper(II) nitrate.

(a)

State the formula of a spectator ion in this reaction.

[1 mark]

(b)

Explain what is meant by the term 'spectator ion'.

[1 mark]

(c)

Identify the spectator ion(s) in the following equation:

[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) NO_3^-

(b) An ion that does not take part in the chemical reaction and remains unchanged on both sides of the equation.

Common mistakes: Omitting nitrate ion charge; Confusing reactants and products

Show mark scheme and worked solution

Marking points

B1 (a) · 1 mark · States nitrate ion as the spectator ion (accept NO3^-, nitrate).

B2 (b) · 1 mark · Explains correctly that a spectator ion is unchanged in the reaction.

B3 (c) · 2 marks · Correctly identifies nitrate as the only spectator ion. Award 1 mark if answer is correct but not fully explained.

Worked solution

a) The formula of a spectator ion is NO3^-.

b) A spectator ion does not change during the reaction: it remains chemically the same on both sides of the equation.

c) Looking at the equation, nitrate ions ( NO_3^- ) appear in the same form on both sides and do not undergo change. Thus, nitrate is the spectator ion.