Question

The extent of charge of lead accumulator is determined by:
A. Amount of ${\text{PbS}}{{\text{O}}_{\text{4}}}$ in the battery
B. Amount of ${\text{Pb}}{{\text{O}}_2}$ in the battery
C. Specific gravity of ${{\text{H}}_2}{\text{S}}{{\text{O}}_4}$ of the battery
D. Amount of Pb in the battery

Answer 1

to answer this question you should know what a lead accumulator is? A lead accumulator is a rechargeable cell, where electricity can be stored as an external source for future use. This cell can be charged. This is also called Lead-acid battery or lead storage battery.

Complete step by step solution:
In this secondary cell while production of electricity, lead sulfate is used as both positive and negative electrode. Sulfuric acid solution is taken as an electrolyte of this cell. In this case electrons are produced from the negative electrode and travel to the positive electrode. Due to movement of electrons an electric field is generated which is in the opposite direction of electron movement.
The reactions at negative and positive electrodes are,
${\text{Pb(s) + HS}}{{\text{O}}_{\text{4}}}^{\text{ - }}{\text{(aq)}} \to {\text{PbS}}{{\text{O}}_{\text{4}}}{\text{(s) + }}{{\text{H}}^{\text{ + }}}{\text{(aq) + 2}}{{\text{e}}^{\text{ - }}}$
${\text{Pb}}{{\text{O}}_{\text{2}}}{\text{(s) + HS}}{{\text{O}}_{\text{4}}}^{\text{ - }}{\text{(aq) + 3}}{{\text{H}}^{\text{ + }}}{\text{(aq) + 2}}{{\text{e}}^{\text{ - }}} \to {\text{PbS}}{{\text{O}}_{\text{4}}}{\text{(s) + 2}}{{\text{H}}_{\text{2}}}{\text{O}}$
The overall cell reaction is,
${\text{Pb}}{{\text{O}}_{\text{2}}}{\text{(s) + Pb(s) + 2}}{{\text{H}}_2}{\text{S}}{{\text{O}}_{\text{4}}}{\text{(aq)}} \to 2{\text{PbS}}{{\text{O}}_{\text{4}}}{\text{(s) + 2}}{{\text{H}}_{\text{2}}}{\text{O}}$
Now, to understand the quality of its power the lead accumulator, specific gravity or density of the acid solution plays a vital role. Higher the value of the specific gravity higher will be charge accommodation of the battery, or you can say higher will be the extent of charge of the battery.
So, the extent of charge of lead accumulator is determined by the specific gravity of sulfuric acid solution (${{\text{H}}_2}{\text{S}}{{\text{O}}_4}$solution).

The correct option is C.

Note: Dilute Sulfuric acid solution is taken as an electrolyte of lead accumulator. This cell can be recharged , where electricity can be stored as an external source for future use. In the solution of sulfuric acid there are 65% water and 35% sulfuric acid. During charging the battery the value of the specific gravity increases and while discharging the value of specific gravity decreases.