Question

A solution containing $4.2g$ of $KOH$ and $Ca(OH{)}_2$ is neutralised by an acid. If it consumes $0.1gramequivalents$ of the acid, calculate the composition of the sample.

Answer 1

Let mass of $KOH$ be present in mixture $=ag$
and Mass of $Ca(OH{)}_2=(4.2-a)g$
Eq. mass of $KOH=56$; Eq. mass of $Ca(OH{)}_2=\frac{74}{2}=37$
$g$ equivalent of $KOH+g$ equivalent of $Ca(OH{)}_2=g$ equivalent of the acid
$\frac{a}{56}+\frac{(4.2-a)}{37}=0.1$
or $37a-56a=0.1\times 56\times 37-4.2\times 56$
or $19a=28$
$a=\frac{28}{19}=1.47$
Mass of $KOH$ in the sample $=1.47g$
Percentage of $KOH=35$
and Percentage of $Ca(OH{)}_2=100-35=65$.