Question

The extent of charge of lead accumulator is determined by

• A. amount of $PbSO _{4}$ in the battery
• B. amount of $PbO _{2}$ in the battery
• C. specific gravity of $H _{2} SO _{4}$ of the battery
• D. amount of $Pb$ in the battery

Answer 1

Answer: (C)

In a fully charged lead accumulator or lead storage battery, sulphuric acid has a specific gravity (i.e., density that varies from $1.260$ to 1.285. But during discharge (i.e., when the battery is in use). $H _{2} SO _{4}$ is used up.

$Pb ( s )+ PbO _{2}( s )+4 H ^{+}( aq )+2 SO _{4}^{2-}( aq ) \longrightarrow 2 PbSO _{4}(l)+2 H _{2} O$

As a result, the specific gravity of $H _{2} SO _{4}$ falls when it falls below $1.230$ the battery needs recharging.