A student monitors the concentration of ethanoic acid in a household vinegar sample over time by titrating 25.0 cm3 aliquots against a standard solution of 0.100 mol dm−3 NaOH0.100\text{ mol dm}^{-3}\ \text{NaOH}0.100 mol dm−3 NaOH. The burette readings from the titrations are shown in the table below:
| Titration 1 (rough) | Titration 2 | Titration 3 | Titration 4 | |
|---|---|---|---|---|
| Final reading (cm3)(\text{cm}^3)(cm3) | 25.10 | 24.45 | 47.95 | 24.95 |
| Initial reading (cm3)(\text{cm}^3)(cm3) | 0.50 | 0.50 | 24.30 | 1.10 |
What is the accurate average titre that the student should use to calculate the concentration of ethanoic acid?
23.82 cm323.82\text{ cm}^323.82 cm3
23.90 cm323.90\text{ cm}^323.90 cm3
24.01 cm324.01\text{ cm}^324.01 cm3
23.75 cm323.75\text{ cm}^323.75 cm3
91 exam-style questions on OCR GCSE Chemistry Monitoring chemical reactions. Each one has a worked solution and a mark scheme showing where the marks go.