A student uses a titration to find the concentration of hydrochloric acid. The student puts 25.0 cm3\mathrm{cm^{3}}cm3 of sodium hydroxide solution with a concentration of 0.0800 mol/dm3\mathrm{mol/dm^{3}}mol/dm3 into a conical flask. The student adds a few drops of methyl orange indicator. Hydrochloric acid is added from a burette.
HCl(aq)+NaOH(aq)→NaCl(aq)+H2O(l) \mathrm{HCl(aq)} + \mathrm{NaOH(aq)} \rightarrow \mathrm{NaCl(aq)} + \mathrm{H_{2}O(l)} HCl(aq)+NaOH(aq)→NaCl(aq)+H2O(l)| Run | Initial burette reading (cm3\mathrm{cm^{3}}cm3) | Final burette reading (cm3\mathrm{cm^{3}}cm3) |
|---|---|---|
| Rough | 0.00 | 20.70 |
| Accurate 1 | 0.10 | 20.05 |
| Accurate 2 | 0.00 | 20.05 |
Complete the observation record for the titration.
Colour of the solution before acid is added: ______
Colour at the end point: ______
For each accurate run, work out the volume of hydrochloric acid delivered. Use the accurate runs to determine the average volume delivered.
Complete the working to find the concentration of hydrochloric acid.
Moles of sodium hydroxide = ______ mol
Moles of hydrochloric acid at the end point = ______ mol
Concentration of hydrochloric acid = ______ mol/dm3\mathrm{mol/dm^{3}}mol/dm3
152 exam-style questions on OCR GCSE Chemistry 5.1 Monitoring chemical reactions, covering 5.1.1 The technique of titration, 5.1.2 Theoretical mass, percentage yield and atom economy, 5.1.3 Concentration of a solution in mol/dm3, 5.1.4 Concentration calculations and titration results, 5.1.5 Molar gas volume and volumes of gases in reactions, and 5.1.6 Choosing a reaction pathway. Each one has a worked solution and a mark scheme showing where the marks go.