A student electroplates a copper spoon with silver. The spoon is one electrode and a silver bar is the other. The electrolyte is silver nitrate solution.
Which half equations show the reactions at the electrodes?
Anode: Ag→Ag++e−\mathrm{Ag \rightarrow Ag^{+} + e^{-}}Ag→Ag++e−; cathode: Ag++e−→Ag\mathrm{Ag^{+} + e^{-} \rightarrow Ag}Ag++e−→Ag
Anode: Ag++e−→Ag\mathrm{Ag^{+} + e^{-} \rightarrow Ag}Ag++e−→Ag; cathode: Ag→Ag++e−\mathrm{Ag \rightarrow Ag^{+} + e^{-}}Ag→Ag++e−
Anode: 4OH−→O2+2H2O+4e−\mathrm{4OH^{-} \rightarrow O_{2} + 2H_{2}O + 4e^{-}}4OH−→O2+2H2O+4e−; cathode: Ag++e−→Ag\mathrm{Ag^{+} + e^{-} \rightarrow Ag}Ag++e−→Ag
Anode: Ag→Ag++e−\mathrm{Ag \rightarrow Ag^{+} + e^{-}}Ag→Ag++e−; cathode: 2H++2e−→H2\mathrm{2H^{+} + 2e^{-} \rightarrow H_{2}}2H++2e−→H2
52 exam-style questions on OCR GCSE Chemistry 3.4 Electrolysis, covering 3.4.1 Products formed at the electrodes in electrolysis and 3.4.2 The technique of electrolysis. Each one has a worked solution and a mark scheme showing where the marks go.