Magnesium is extracted by the electrolysis of molten magnesium chloride, MgCl2\text{MgCl}_2MgCl2.
Which equation shows the reaction at the anode in this electrolysis?
Mg2++2e−→Mg\text{Mg}^{2+} + 2\text{e}^- \rightarrow \text{Mg}Mg2++2e−→Mg
2Cl−−2e−→Cl22\text{Cl}^- - 2\text{e}^- \rightarrow \text{Cl}_22Cl−−2e−→Cl2
2H++2e−→H22\text{H}^+ + 2\text{e}^- \rightarrow \text{H}_22H++2e−→H2
4OH−−4e−→O2+2H2O4\text{OH}^- - 4\text{e}^- \rightarrow \text{O}_2 + 2\text{H}_2\text{O}4OH−−4e−→O2+2H2O
34 exam-style questions on OCR GCSE Chemistry Electrolysis. Each one has a worked solution and a mark scheme showing where the marks go.