A lead storage battery consists of a lead anode and a grid of lead packed with lead dioxide as the cathode. The electrolyte taken is 39% `H_(2)SO_(4)` by mass having a density of 1.294 g `mL^(-1)`. The battery holds 3.5 L of the acid. During the discharge of the battery, the density `H_(2)SO_(4)` falls from 1.294 g `mL^(-1)` to 1.139 g `mL^(-1)` which is 20% `H_(2)SO_(4)` by mass
Q. Moles of sulphuric acid lost during discharge is

Options

A. 9.88
B. 8.88
C. 2.32
D. 1.16

Answer

A

Explanation

Mass of the solution before discharge
`=3500mLxx1.294" g "mL^(-1)=4529g`
mass of `H_(2)SO_(4)` present in this solution
`=(39)/(100)xx4529g=1766.31g`
mass of the solution of after discharge
`=3500mLxx1.139" g "mL^(-1)=3986.5g`
mass of `H_(2)SO_(4)` present in this soluton,
`=(20)/(100)xx3986.5=797.3g`
Loss in mass of `H_(2)SO_(4)` during discharge
`=1766.31-797.3=969.01g`
Moles of `H_(2)SO_(4)` lost during discharge
`=(969.01)/(98)=9.88786`