Old mobile phones contain valuable metals. Gold is used for the electrical connectors on circuit boards.
1 tonne of phone circuit boards contains 250 g of gold. 1 tonne of gold ore contains 5.0 g of gold.
Explain why gold is used for electrical connectors, even though it is expensive.
A recycling plant processes 120 tonnes of phone circuit boards each year. It recovers 92% of the gold. Calculate the mass of gold recovered each year. Give your answer in kilograms.
Determine the mass of gold ore that would have to be mined to obtain the same mass of gold as the plant recovers each year.
Only a small percentage of old mobile phones is recycled. Suggest two reasons why.
Copper is also recovered. The circuit boards are treated to produce a solution of copper(II) ions, and copper is then deposited by electrolysis using inert electrodes. Write the half equation for the formation of copper at the cathode.
Oxygen forms at the anode: 4OH−→O2+2H2O+4e−4\mathrm{OH^{-}} \rightarrow \mathrm{O_{2}} + 2\mathrm{H_{2}O} + 4\mathrm{e^{-}}4OH−→O2+2H2O+4e− Calculate the volume of oxygen, in dm3\mathrm{dm^{3}}dm3, produced at the anode while 127 kg of copper is deposited at the cathode. Relative atomic mass: Cu = 63.5. One mole of any gas occupies 24 dm3\mathrm{dm^{3}}dm3 at room temperature and pressure.
45 exam-style questions on Edexcel GCSE Chemistry 5.1 Obtaining and using metals, covering 5.1.1 The reactivity series of metals, 5.1.2 Displacement reactions as redox reactions, 5.1.3 Extracting metals from ores by reduction, 5.1.4 Biological methods of metal extraction, 5.1.5 Resistance to oxidation and recycling metals, and 5.1.6 Life cycle assessment. Each one has a worked solution and a mark scheme showing where the marks go.