A metal-recovery plant obtains copper by electrolysing a solution containing a copper compound.
A technician uses a new negative electrode for each electrolysis. All conditions are kept the same except for the duration of electrolysis.
| Duration of electrolysis in minutes | Mass of negative electrode before electrolysis in g | Mass of negative electrode after electrolysis in g |
|---|---|---|
| 5.0 | 18.42 | 18.57 |
| 10.0 | 18.37 | 18.67 |
| 15.0 | 18.45 | 18.90 |
Explain why the mass of each negative electrode increased.
A fourth negative electrode has a mass of 18.40 g before electrolysis.
Calculate the expected mass of this electrode after 20.0 minutes of electrolysis.
Assume the pattern in the results continues.
87 exam-style questions on AQA GCSE Chemistry 10.1 Using the Earth's resources and obtaining potable water, covering 10.1.1 Using the Earth's resources and sustainable development, 10.1.2 Potable water, 10.1.3 Waste water treatment, and 10.1.4 Alternative methods of extracting metals. Each one has a worked solution and a mark scheme showing where the marks go.