Calculations with equations involving solutions

2 marks · Hard

Sodium carbonate reacts with hydrochloric acid according to the following equation:

If 0.06 mol of hydrochloric acid, HCl, are used in the reaction, calculate the number of moles of sodium carbonate, Na2CO3, that will completely react.

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0.03 mol (±0.005)

Also accept: 3.0 × 10^{-2} mol; 3×10^{-2} mol

Common mistakes: Not dividing by 2 for correct ratio

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Marking points

M1 · 1 mark · Correctly identifies from the equation that 2 mol HCl react with 1 mol Na2CO3 (ratio 2:1).

A1 · 1 mark · Correctly calculates number of moles of Na2CO3 (= 0.06 ÷ 2 = 0.03 mol).

Worked solution

From the equation, 2 mol of HCl react with 1 mol of Na2CO3.

So if 0.06 mol of HCl are used: