Question

The equivalent weight of KIO3 in the given reaction is (M=molecular mass) :
2Cr(OH)3 + 4OH + KIO3 → 2CrO42- + 5H2O +KI

• A. $M$
• B. $\frac{M}{2}$
• C. $\frac{M}{6}$
• D. $\frac{M}{8}$

Answer 1

Answer: (C)

$\frac{M}{6}$

Answer 2

The correct answer is option (C): $\frac{M}{6}$
The balanced chemical reaction is $2Cr(OH)_3​+OH^−+KIO_3​⟶2CrO_4^{2−}​+KI+5H_2​O$
The oxidation number of iodine changes from +5 to -1.
The change in the oxidation number is 6.
The equivalent mass of potassium iodate is $\frac{\text{Molar\,mass\,of\,potassium\,iodate}}{\text{Change\,in\, the \,oxidation\,number\,of\,iodine}}=\frac{253.34}{3}=84.44=\frac{M}{6}$