Question

Write the ion electron equations for the half cell reactions and overall cell reaction for the cell.

\[\ce{Pt, H2_{(g)} | HCl_{(aq)} || Fe^{3+}, Fe^{2+} | Pt}\]

Answer 1

Given: \[\ce{Pt, H2_{(g)} | HCl_{(aq)} || Fe^{3+}, Fe^{2+} | Pt}\]

Anode (oxidation): 

At the hydrogen electrode, hydrogen gas is oxidised to H⁺:

\[\ce{H2_{(g)} −> 2H{^{+}_{(aq)}} + 2e-}\]

Cathode (reduction):

At the iron half-cell, Fe³⁺ is reduced to Fe²⁺:

\[\ce{Fe{^{3+}_{(aq)}} + e- -> Fe{^{2+}_{(aq)}}}\]

To balance electrons, multiply the Fe³⁺ reaction by 2:

\[\ce{2Fe^3+ + 2e- -> 2Fe^3+}\]

Net cell reaction:

\[\ce{H2_{(g)} + 2Fe{^{3+}_{(aq)}} −> 2H{^{+}_{(aq)}} + 2Fe{^{2+}_{(aq)}}}\]