Question

When the lead storage battery is in use (during discharge) the reaction that occurs at the anode is

• A. PbSO\(_4\)(s) + 2H\(_2\)O(\(l\)) $\longrightarrow$ PbO\(_2\)(s) + SO\(_4^{2-}\)(aq) + 4H\(^{+}\)(aq) + 2e\(^-\)
• B. Pb(s) + PbO\(_2\)(s) + 2H\(_2\)SO\(_4\)(aq) $\longrightarrow$ 2PbSO\(_4\)(s) + 2H\(_2\)O(\(l\))
• C. Pb(s) + SO\(_4^{2-}\)(aq) $\longrightarrow$ PbSO\(_4\)(s) + 2e\(^-\)
• D. PbO\(_2\)(s) + SO\(_4^{2-}\)(aq) + 4H\(^{+}\)(aq) + 2e\(^-\) $\longrightarrow$ PbSO\(_4\)(s) + 2H\(_2\)O(\(l\))

Hint:

In a lead storage battery during discharge: - Anode (Negative Electrode):} Lead (Pb) is oxidized to lead sulfate (PbSO\(_4\)). Reaction: Pb(s) + SO\(_4^{2-}\)(aq) $\longrightarrow$ PbSO\(_4\)(s) + 2e\(^-\) - Cathode (Positive Electrode):} Lead dioxide (PbO\(_2\)) is reduced to lead sulfate (PbSO\(_4\)). Reaction: PbO\(_2\)(s) + SO\(_4^{2-}\)(aq) + 4H\(^{+}\)(aq) + 2e\(^-\) $\longrightarrow$ PbSO\(_4\)(s) + 2H\(_2\)O(\(l\)) Remember that oxidation always occurs at the anode and reduction at the cathode in any electrochemical cell.

Answer 1

The Correct Option is C

Step 1: Understand the operation of a lead storage battery during discharge.
A lead storage battery is a secondary (rechargeable) electrochemical cell. During discharge, it acts as a galvanic cell, converting chemical energy into electrical energy. In a galvanic cell, oxidation occurs at the anode (negative electrode) and reduction occurs at the cathode (positive electrode). 
Step 2: Identify the anode and cathode materials in a lead storage battery.
In a lead storage battery:
The anode (negative electrode) is made of spongy lead (Pb). The cathode (positive electrode) is made of lead dioxide (PbO\(_2\)). The electrolyte is an aqueous solution of sulfuric acid (H\(_2\)SO\(_4\)). 
Step 3: Determine the reaction occurring at the anode during discharge.
At the anode, oxidation takes place. Lead metal (Pb) from the anode reacts with sulfate ions (SO\(_4^{2-}\)) from the sulfuric acid electrolyte to form lead sulfate (PbSO\(_4\)) and release electrons. The oxidation state of Pb changes from 0 in Pb(s) to +2 in PbSO\(_4\)(s), indicating oxidation. The half-reaction at the anode is: Pb(s) + SO\(_4^{2-}\)(aq) $\longrightarrow$ PbSO\(_4\)(s) + 2e\(^-\) 
Step 4: Verify the other options to ensure the correct anode reaction is selected.
Option 1: PbSO\(_4\)(s) + 2H\(_2\)O(\(l\)) $\longrightarrow$ PbO\(_2\)(s) + SO\(_4^{2-}\)(aq) + 4H\(^{+}\)(aq) + 2e\(^-\) This reaction shows PbSO\(_4\) being oxidized to PbO\(_2\). This is the reaction that occurs at the cathode (PbO\(_2\)) during charging (or reduction of PbO\(_2\) to PbSO\(_4\) at the cathode during discharge is the reverse process). This is not the anode reaction during discharge. 
Option 2: Pb(s) + PbO\(_2\)(s) + 2H\(_2\)SO\(_4\)(aq) $\longrightarrow$ 2PbSO\(_4\)(s) + 2H\(_2\)O(\(l\)) This is the overall discharge reaction of the lead storage battery, not specifically the anode reaction. 
Option 4: PbO\(_2\)(s) + SO\(_4^{2-}\)(aq) + 4H\(_H^{+}\)(aq) + 2e\(^-\) $\longrightarrow$ PbSO\(_4\)(s) + 2H\(_2\)O(\(l\)) This reaction shows PbO\(_2\) being reduced to PbSO\(_4\). This is the reaction that occurs at the cathode during discharge. Therefore, based on the principle of oxidation at the anode during discharge, Option 3 correctly represents the anode reaction. 
The final answer is $\boxed{Pb(s) + SO}_4^{2-}(aq)} \longrightarrow PbSO}_4(s) + 2e}^-}$.