A student makes a chemical cell. A strip of magnesium is placed in magnesium sulfate solution and a strip of copper is placed in copper sulfate solution. The two solutions are joined by a strip of filter paper soaked in potassium nitrate solution, and the two metals are connected to a voltmeter. The overall reaction in the cell is:
Mg(s)+Cu2+(aq)→Mg2+(aq)+Cu(s)\mathrm{Mg(s)} + \mathrm{Cu^{2+}(aq)} \rightarrow \mathrm{Mg^{2+}(aq)} + \mathrm{Cu(s)}Mg(s)+Cu2+(aq)→Mg2+(aq)+Cu(s)
Write the half equation for the reaction at the magnesium electrode.
Explain, in terms of electrons, why the overall reaction is a redox reaction.
After the cell has been used for some time, the magnesium strip has lost 0.36 g. Calculate the mass of copper that has been deposited on the copper strip. Relative atomic masses: Mg = 24, Cu = 63.5
The student replaces the magnesium with zinc and the magnesium sulfate with zinc sulfate. Predict how the voltage changes and explain your answer.
The copper sulfate solution is blue at the start. Predict how the colour of the copper sulfate solution changes as the cell is used. Explain your answer.
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.