Making insoluble salts

3 marks · Normal

A precipitation reaction is carried out by mixing 50 cm^3 of 0.1 mol/dm^3 barium nitrate solution with excess potassium sulfate solution. The reaction forms barium sulfate as a precipitate according to the equation:

State the formula of the precipitate and name one spectator ion in the reaction.

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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(i) BaSO4

(ii) K+ or NO3-

Also accept: Formula: BaSO4; Spectator ions: K+ or NO3-

Common mistakes: Giving a product as the spectator ion; Missing state symbols

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Marking points

B1 · 1 mark · States the correct formula for the precipitate (BaSO4).

B2 · 1 mark · States one correct spectator ion: K+ or NO3-.

B3 · 1 mark · Uses the correct notation or state symbols for both answers.

Worked solution

The solid that forms is barium sulfate, so the formula of the precipitate is BaSO4.

Spectator ions are ions that do not form the precipitate. In this reaction, K+ and NO3- remain in solution, so either can be named as a spectator ion.