Question

The equivalent weight of KIO₃ in the given reaction is (M=molecular mass) :
2Cr(OH)₃ + 4OH + KIO₃ → 2CrO₄^2- + 5H₂O +KI

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

Answer 1

The Correct Option is C

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 \(\frac{\text{Molar\,mass\,of\,potassium\,iodate}}{\text{Change\,in\, the \,oxidation\,number\,of\,iodine}}=\frac{253.34}{3}=84.44=\frac{M}{6}\)

Answer 2

(a) KIO₃ it acts as an oxidizing agent in the given redox reaction.
(b) There is change in oxidation number of iodine (in reactant) +5 to −1 (in product).
→ KIO₃O.S →+1 + x - 6 = +5
→ In KI O.S → x + 1 = -1
Therefore, I has Oxidation no. +5 in KIO₃
Also, I has Oxidation no. -1 in KI
change in oxidation number from +5 to -1 :
+4, +3, +2, +1, 0, -1 = 6
Hence,
Equivalent mass of KIO₃ = \(\frac{\text{Molar Mass}}{6}\)
So, the correct option is (C) : \(\frac{M}{6}\).