A hydrogen fuel cell powers an automatic warning beacon. Hydrogen and oxygen are supplied continuously, and the cell is connected in a complete circuit. Hydrogen ions move through the electrolyte inside the cell.
An engineer proposes the following half equation for the reaction at the oxygen electrode:
O2+4H+→2H2O+4e−\text{O}_2 + 4\text{H}^+ \rightarrow 2\text{H}_2\text{O} + 4e^-O2+4H+→2H2O+4e−
Explain why the proposed half equation is not correct.
The oxygen supply is stopped while hydrogen continues to be supplied. State what happens to the current produced by the cell. Explain your answer.
90 exam-style questions on AQA GCSE Chemistry 5.2 Chemical cells and fuel cells, covering 5.2.1 Cells and batteries, 5.2.2a Fuel cells, and 5.2.2b Half equations for hydrogen fuel cells. Each one has a worked solution and a mark scheme showing where the marks go.