Question

$1.25$ g of a sample of bleaching powder was dissolved in $100$ ml of water and $25$ ml of which are titrated with $KI$ solution. The iodine liberated required $12.5$ ml of $\frac{N}{25}$ hypo-solution in titration. The percentage of chlorine in the sample of bleaching powder is:

• A. $5.68\%$
• B. $7.68\%$
• C. $9.68\%$
• D. $10.12\%$

Answer 1

The correct option is A $5.68\%$

The gram equivalents of hypo solution $=\frac{12.5}{25}\times 1000=0.0005$

This is also equal to gram equivalents of iodine atoms

This is also equal to gram equivalents of chlorine atoms

mass of chlorine atoms in the 25 ml solution $=0.0005\times 35.5$

mass of chlorine atoms $=0.002\times 35.5$

Hence, the percentage of available chlorine is $\frac{0.071}{1.25}\times 100=5.68\%$