Question

1.25 g sample of bleaching powder is dissolved in 100 mL of water and 25 mL of which is treated with $KI$ solution. The iodine so liberated required 12.5 mL of $\frac{N}{25}$ hypo solution. Find the percentage of chlorine available from the sample of bleaching powder

• A. 5.68 %
• B. 10.09 %
• C. 15.31 %
• D. 12.31 %

Answer 1

The correct option is A 5.68 %

m.e. of available chlorine in 25 mL of bleaching powder
= m.e of iodine liberated
= m.e of hypo solution
= $\frac{1}{25}\times 12.5=0.5$
m.e. of available chlorine in 25 mL of bleaching powder = $\frac{0.5\times 100}{25}=2$
equivalents of available chlorine = $\frac{2}{1000}$
wt. of available chlorine = $\frac{2}{1000}\times 35.5=0.071g$
percentage of available chlorine = $\frac{0.071}{1.25}\times 100=5.68\%$