Gold nanoparticles can be used as catalysts. Scientists model particles of gold as cubes.
For a cube with sides of length L:
• surface area=6×L×L\text{surface area} = 6 \times L \times Lsurface area=6×L×L
• volume=L×L×L\text{volume} = L \times L \times Lvolume=L×L×L
The table shows information about cubes of different sizes.
| Length of side / nm | Surface area / nm2\mathrm{nm^{2}}nm2 | Volume / nm3\mathrm{nm^{3}}nm3 | Surface area to volume ratio |
|---|---|---|---|
| 1 | 6 | 1 | 6 |
| 10 | 600 | 1000 | 0.6 |
| 100 | A | 1 000 000 | B |
Calculate value A.
Calculate value B. Use the equation: surface area to volume ratio=surface areavolume\displaystyle \text{surface area to volume ratio} = \frac{\text{surface area}}{\text{volume}}surface area to volume ratio=volumesurface area
Describe how the surface area to volume ratio changes as the length of side increases. Use data from the table in your answer.
Explain why a catalyst made of gold nanoparticles can be more effective than the same mass of gold as a coarse powder.
Gold is very expensive. Suggest one advantage of using gold nanoparticles as a catalyst.
36 exam-style questions on Edexcel GCSE Chemistry 10.5 Bulk and surface properties of matter including nanoparticles, covering 10.5.1 Nanoparticles: size, uses and risks and 10.5.2 Comparing and selecting materials. Each one has a worked solution and a mark scheme showing where the marks go.