Reversing the calculations
2 marks · HardA student wants to completely neutralise 10.0 cm³ of 0.200 mol/dm³ nitric acid with sodium carbonate solution. The balanced equation for the reaction is:
Calculate the minimum volume, in cm³, of 0.100 mol/dm³ sodium carbonate solution required to react fully with the nitric acid.
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
5.00 cm³ (±0.05)
Also accept: Work shown in dm³ before converting to cm³
Common mistakes: Incorrectly uses 1:1 instead of 1:2 mole ratio; Fails to convert volume units correctly
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Marking points
M1 · 1 mark · Correct calculation of moles of HNO3 and correct use of stoichiometric ratio to find moles of Na2CO3 required.
A1 · 1 mark · Correct final answer (5.00 cm³) with working and correct unit (cm³). (follow-through)
Worked solution
Number of moles of HNO3 =
From the equation, 2 mol HNO3 reacts with 1 mol Na2CO3, so moles Na2CO3 required:
Volume needed (in dm³):
Convert to cm³: