During the recharging of lead acid storage cell the reaction at anode is

Options

A. `Pb^(2+) rarr Pb`
B. `Pb^(2+) rarr Pb^(4+)`
C. `Pb rarr Pb^(2+)`
D. `Pb^(4+) rarr Pb^(2+)`

Answer

To determine the reaction at the anode during the recharging of a lead-acid storage cell, we need to understand the processes involved in both discharging and recharging the battery.

### Step-by-Step Solution:

1. **Understand the Discharge Reaction**:
- When a lead-acid battery discharges, the anode reaction involves lead (Pb) and lead sulfate (PbSO4). The overall reaction can be summarized as:
\[ \text{Pb (s) + PbSO}_4 (s) + 2 \text{H}_2\text{SO}_4 (aq) \rightarrow 2 \text{PbSO}_4 (s) + 2 \text{H}_2\text{O} (l) \]
- At the anode during discharge, lead (Pb) is oxidized to lead sulfate (PbSO4), and electrons are released.

2. **Identify the Reaction During Charging**:
- During the recharging process, the reactions at the anode and cathode are reversed. Therefore, we need to write the anode reaction in reverse.
- The anode reaction during charging can be represented as:
\[ \text{PbSO}_4 (s) + 2 \text{H}_2\text{O} (l) \rightarrow \text{PbO}_2 (s) + \text{H}_2\text{SO}_4 (aq) + 4 \text{H}^+ + 2 \text{e}^- \]

3. **Analyze the Oxidation Process**:
- At the anode, oxidation occurs, which means that there is a loss of electrons. In this case, lead sulfate (PbSO4) is converted back to lead dioxide (PbO2).
- The oxidation state of lead changes from +2 in lead sulfate to +4 in lead dioxide.

4. **Final Reaction at the Anode**:
- Therefore, the reaction at the anode during the recharging of a lead-acid battery is:
\[ \text{PbSO}_4 (s) + 2 \text{H}_2\text{O} (l) \rightarrow \text{PbO}_2 (s) + \text{H}_2\text{SO}_4 (aq) + 4 \text{H}^+ + 2 \text{e}^- \]

### Conclusion:
The reaction at the anode during the recharging of a lead-acid storage cell involves the conversion of lead sulfate to lead dioxide, accompanied by the release of protons and electrons.

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