2. Electrochemistry — Chemistry STD 12 Science — Question

$P b_{(s)}+P b O_{2(s)}+2 H_{2} S O_{4(a q)} \rightarrow 2 P b S O_{4(s)}+2 H_{2} O_{(l)}$

$\rightarrow$ During discharge, $H_{2} S O_{4}$ is consumed and its density decreases.

$\rightarrow$ Fully charged cell gives a potential of about $2 V$. When the cell potential reduces to about $1.8 V$ it should be recharged.

Net cell reaction during recharge:-

$2 P b S O_{4(s)}+2 H_{2} O_{(l)} \rightarrow P b_{(s)}+P b O_{2(s)}+2 H_{2} S O_{4(a q)}$

$\rightarrow$ The concentration of $H_{2} S O_{4}$ increases as it is generated.