Some Basic Concepts of Chemistry - Result Question 34

Subjective Questions

35. To a $25 \mathrm{~mL} \mathrm{H}_2 \mathrm{O}_2$ solution, excess of acidified solution of potassium iodide was added. The iodine liberated required 20 mL of 0.3 N sodium thiosulphate solution. Calculate the volume strength of $\mathrm{H}_2 \mathrm{O}_2$ solution.

(1997, 5M)

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Answer:

Correct Answer: 35. (1.334 V)

Solution:

  1. Meq of $\mathrm{H}_2 \mathrm{O}_2=$ Meq of $\mathrm{I}_2=$ Meq of $\mathrm{Na}_2 \mathrm{~S}_2 \mathrm{O}_3$ If $N$ is normality of $\mathrm{H}_2 \mathrm{O}_2$, then

$\begin{aligned} N \times 25 & =0.3 \times 20 \\ \Rightarrow \quad N & =0.24 \\ \Rightarrow \text { Volume strength } & =N \times 5.6=1.334 \mathrm{~V} \end{aligned}$