The standard calculation
2 marks · EasyExplain, using the three-step titration calculation method, how you can find the concentration of an unknown acid after titrating it with a solution of known concentration.
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Show answer
First, calculate the moles of the known solution using its concentration and volume. Next, use the balanced chemical equation to find the moles of the unknown solution that reacted. Finally, calculate the concentration of the unknown solution using its moles and volume.
Also accept: Step 1: Calculate moles of known solution. Step 2: Use the equation to get moles of unknown. Step 3: Use the unknown's volume to get its concentration.
Common mistakes: Stating only one or two steps; Not mentioning use of the balanced equation
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Marking points
M1 · 1 mark · Explains calculating moles of standard (known) solution from its volume and concentration.
M2 · 1 mark · States use of moles ratio from balanced equation to find moles of unknown, then concentration of unknown using its moles and volume.
Worked solution
First, calculate the number of moles of the solution with known concentration and volume. Then, use the balanced chemical equation to work out how many moles of the unknown solution were required. Finally, use the unknown's volume in the titration result to calculate its concentration.