Question

100 mL solution of 0.1 M $HCl$ was titrated with 0.2 $NaOH$ solution. The titration was discontinued after the addition of 30 mL of $NaOH$. The remaining titration was completed with the addition of 0.5 M $KOH$. The volume of $KOH$ required for completing the titration is:

• A. $8mL$
• B. $16mL$
• C. $32mL$
• D. $64mL$

Answer 1

The correct option is B $16mL$

For $HCl,KOH$ & $NaOH$ normality $=$ molarity

Moles of $HCl=0.1L\times 0.1N=0.01$

Moles of ${OH}^{-}$ needed $=0.01$

Moles of $NaOH$ added $=0.03\times 0.2=0.006$

Moles of $KOH$ needed $=0.01-0.006=0.004$

$V=0.004/0.25=0.016L=16ml$