Consider an electrochemical cell constructed from the following half cells, linked by an external circuit and by a KCl salt bridge. • an Al(s) electrode in 1.0 M Al(NO₃) ₃ solution
• a Pb(s) electrode in 1.0 M Pb(NO₃) ₂ solution
The balanced overall (net) cell reaction is

Question

Quizplus · Accepted Answer

The overall cell reaction must be balanced in terms of both mass and charge. In this case, the reduction half-reaction for the Al electrode is Al³⁺ + 3e⁻ → Al(s), while the oxidation half-reaction for the Pb electrode is Pb(s) → Pb²⁺ + 2e⁻. To balance the number of electrons, the reduction half-reaction must be multiplied by 2, while the oxidation half-reaction must be multiplied by 3. This gives us the overall balanced equation: 
3Pb(s) + 2Al³⁺ → 3Pb²⁺ + 2Al(s) 
which is equivalent to choice C.

Consider an Electrochemical Cell Constructed from the Following Half Cells →\to→

Consider an Electrochemical Cell Constructed from the Following Half Cells $\to$