MolSynapsequestion bank

MolSynapse / Question bank / d- and f-Block Elements / Important compounds: KMnO4 and K2Cr2O7

JEE Advanced levelOne or more correct optionsDifficulty 3 of 3df110

Using $K = 39$ , $Mn = 55$ , $Cr = 52$ and $O = 16$ , select the correct equivalent masses.

A $KMnO X_{4}$ in acidic medium: 31.6
B $KMnO X_{4}$ in neutral medium (to $MnO X_{2}$ ): 52.7
C $K X_{2} Cr X_{2} O X_{7}$ in acidic medium (to $Cr X^{3 +}$ ): 49.0
D $KMnO X_{4}$ in strongly alkaline medium (to $MnO X_{4} X^{2 -}$ ): 52.7

Answer: A, B, C

Molar masses:

KMnO X_{4} = 158

and

K X_{2} Cr X_{2} O X_{7} = 2 (39) + 2 (52) + 7 (16) = 294

. Acidic permanganate:

158/5 = 31.6

. Neutral:

158/3 = 52.7

. Dichromate:

294/6 = 49.0

. In strongly alkaline medium the n-factor is 1, so the equivalent mass is

158

, not 52.7; (d) is wrong.

Practice d- and f-Block Elements More on Important compounds: KMnO4 and K2Cr2O7

Previous questionNext question

More questions on Important compounds: KMnO4 and K2Cr2O7