A student titrates dilute sulfuric acid against 25.0 cm3\mathrm{cm^{3}}cm3 of potassium hydroxide solution. She uses methyl orange indicator. The table shows her results.
| Titration | Final reading / cm3\mathrm{cm^{3}}cm3 | Initial reading / cm3\mathrm{cm^{3}}cm3 | Titre / cm3\mathrm{cm^{3}}cm3 |
|---|---|---|---|
| rough | 24.80 | 0.00 | 24.80 |
| 1 | 24.10 | 0.50 | 23.60 |
| 2 | 24.90 | 1.20 | 23.70 |
| 3 | 24.15 | 0.00 |
Calculate the titre for titration 3.
Explain which titres the student should use to calculate the mean titre.
Calculate the mean titre.
Suggest one mistake that could have made the titre in titration 3 too high.
Give the colour change of methyl orange at the end point when acid is added to the alkali.
The potassium hydroxide solution was made by dissolving 14.0 g of potassium hydroxide in water to make 250 cm3\mathrm{cm^{3}}cm3 of solution. Calculate the concentration of the solution in g dm−3\mathrm{g\,dm^{-3}}gdm−3.
51 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.