In a hydrogen-oxygen fuel cell with an acidic electrolyte, these reactions happen at the two electrodes.
Negative electrode: H2→2H++2e−\mathrm{H_{2}} \rightarrow 2\mathrm{H^{+}} + 2\mathrm{e^{-}}H2→2H++2e−
Positive electrode: O2+4H++\mathrm{O_{2}} + 4\mathrm{H^{+}} + O2+4H++ ...... e−→2H2O\mathrm{e^{-}} \rightarrow 2\mathrm{H_{2}O}e−→2H2O
Explain, in terms of electrons, whether hydrogen is oxidised or reduced at the negative electrode.
Complete the half equation for the positive electrode by giving the number of electrons.
Combine the two half equations to write the overall equation for the reaction in the fuel cell.
Hydrogen ions, H+\mathrm{H^{+}}H+, move through the electrolyte between the two electrodes. Use the half equations to explain the direction in which the H+\mathrm{H^{+}}H+ ions move.
Suggest why a car powered by a hydrogen fuel cell may not be better for the environment than a petrol car.
38 exam-style questions on Edexcel GCSE Chemistry 6.4 Chemical cells and fuel cells, covering 6.4.1 Chemical cells and fuel cells. Each one has a worked solution and a mark scheme showing where the marks go.