Making insoluble salts
5 marks · HardCopper(II) carbonate is an insoluble salt produced by a precipitation reaction between aqueous copper(II) sulfate and sodium carbonate.
Write the full balanced chemical equation, including state symbols, for this reaction.
State the formula of the spectator ions in this reaction.
Explain why these ions are considered spectator ions.
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.
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(a) \ce{CuSO4(aq) + Na2CO3(aq) -> CuCO3(s) + Na2SO4(aq)} · must show All formulae correct, Balanced equation, State symbols
(b) Na^+ and SO_4^{2-} · must show Both ions present, Correct symbols
(c) Spectator ions do not take part in the reaction; they remain unchanged and dissolved in solution before and after the reaction. · must show Mention do not take part, Remain unchanged, Remain in solution
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Correct formulae for reactants and products (accept full or ionic forms).
A1 (a) · 1 mark · Balanced equation with all correct state symbols.
B1 (b) · 1 mark · Both sodium (Na^+) and sulfate (SO_4^{2-}) ions identified as spectator ions.
E1 (c) · 1 mark · States that spectator ions do not take part in the reaction.
E2 (c) · 1 mark · States that spectator ions remain unchanged and dissolved (in solution) after the reaction.
Worked solution
a) Full balanced chemical equation:
b) The spectator ions are Na^+ and SO_4^{2-}.
c) Spectator ions are present in the solution before and after the reaction but do not form part of the precipitate or take part in the main reaction. They remain dissolved and unchanged, simply 'watching' the reaction.