25 mL$$ H_2O_2 $$ were added to excess of acidified solution of KI. The iodine so liberated required 20 mL of 0.1 N sodium thiosulphate for titration. Calculate the volume strength.
Milliequivalents of $$Na_2S_2O_3$$ = 20×0.1 = 2
Milliequivalents of $$I_2 =2$$
Milliequivalents of $$KI = 2$$
Milliequivalents of $$H_2O_2 = 2$$
Normality of $$H_2O_2 =\frac{2}{25}$$
For $$H_2O_2$$, 5.6× Normality = Volume strength
∴ Volume strength=$$\frac{2}{25}×5.6=0.448$$