An analyst performed a redox titration to determine the concentration of iron(II) ions in a sample of river water using standard potassium manganate(VII) solution. The table below shows the results of the titrations.
| Rough titration | Accurate titration 1 | Accurate titration 2 | Accurate titration 3 | |
|---|---|---|---|---|
| Final reading on burette in cm3\text{cm}^3cm3 | 16.35 | 15.90 | 16.75 | 17.30 |
| Initial reading on burette in cm3\text{cm}^3cm3 | 0.50 | 0.45 | 1.20 | 1.80 |
| Volume of potassium manganate(VII) solution added in cm3\text{cm}^3cm3 | 15.45 | 15.55 | 15.50 |
Calculate the mean volume of potassium manganate(VII) solution used in the accurate titrations.
157 exam-style questions on Edexcel GCSE Chemistry 6.2 Quantitative analysis, covering 6.2.1 Concentration in mol dm⁻³ and titration calculations, 6.2.2 Percentage yield and why actual yield falls short, 6.2.3 Atom economy of a reaction, 6.2.4 Choosing a reaction pathway, and 6.2.5 Molar volume of gases and Avogadro's law. Each one has a worked solution and a mark scheme showing where the marks go.