Calculate the weight of `90%` pure sulphuric acid to neutralize `5g` caustic soda.

Options

A. `19.19`
B. `6.81`
C. `11.11`
D. None of these

Answer

B

Explanation

Writing the equation for the above reaction
`{:(2NaOH+,,H_(2)SO_(4),rarr,Na_(2)SO_(4)+2H_(2)O),(2 mol es,,1 mol e,,),(or 80g,,,or 98g,):}`
No. of moles in `5 g` caustic soda `=(5)/(40)`
`2` mole of `NaOH` need for neutralization `=1 `mole of `H_(2)SO_(4)`
`:. (5)/(40)` mole of `NaOH` need for neutralization `=(1)/(2)xx(5)/(40)=(1)/(16)mol.`
Amount of `H_(2)SO_(4)` in `g=(1)/(16)xx98g H_(2)SO_(4)=6.13g`
Amount of `90%` pure `H_(2)SO_(4)=6.13xx(100)/(90)=6.81`