A water-treatment process uses a solid reactant to remove a dissolved impurity. Four cuboid elements are made from the same solid, and each has a volume of 24 cm324\,\mathrm{cm^{3}}24cm3.
Each element is placed in a separate sample of water. The samples have the same volume and impurity concentration, and are kept at the same temperature.
| Element | Dimensions |
|---|---|
| W | 1.5 cm×4 cm×4 cm1.5\,\mathrm{cm} \times 4\,\mathrm{cm} \times 4\,\mathrm{cm}1.5cm×4cm×4cm |
| X | 1 cm×4 cm×6 cm1\,\mathrm{cm} \times 4\,\mathrm{cm} \times 6\,\mathrm{cm}1cm×4cm×6cm |
| Y | 2 cm×2 cm×6 cm2\,\mathrm{cm} \times 2\,\mathrm{cm} \times 6\,\mathrm{cm}2cm×2cm×6cm |
| Z | 1 cm×3 cm×8 cm1\,\mathrm{cm} \times 3\,\mathrm{cm} \times 8\,\mathrm{cm}1cm×3cm×8cm |
Which two elements have the same initial rate of reaction with the impurity?
Elements X and Y
Elements W and X
Elements W and Y
Elements X and Z
122 exam-style questions on OCR GCSE Chemistry 5.2 Controlling reactions, covering 5.2.1 Measuring and interpreting rate of reaction, 5.2.2 Factors affecting rate and collision theory, and 5.2.3 Catalysts, activation energy and enzymes. Each one has a worked solution and a mark scheme showing where the marks go.