Q 1. What is the equivalent
wt. of KMnO4 in :
(a) Acidic Medium (b)
Neutral Medium (c) In alkaline Medium
Ans. (a) In Acidic Medium
the reaction is :
5 e– + 8 H+ + MnO4– ———® 4 H2O + Mn2+
M/5 =158/5 = 31.6 g
(b) In
Neutral Medium the reaction is :
MnO4– + 2 H2O + 3 e– ———® MnO2 + 4 OH–
\ eq. wt. = M/3 =158/3 = 52.67
(c) In
Alkaline Medium the reaction is :
(i) Strongly Alkaline Medium
MnO4– + e– ———® MnO42–
magnate ion
M/1 =158/1 = 158
(ii) In Weakly Alkaline Medium the reaction is
:
MnO4– + 2 H2O + 3 e– ———® MnO2 + 4 OH–
Same as in
neutral medium
M/3 =158/3 = 52.67
Q 2 . Sc3+ is more stable
than Sc2+.
Ans. Sc = 1s² 2s² 2p6 3s² 3p6 3d¹ 4s²
Sc3+ = 1s² 2s² 2p6 3s² 3p6
Inert gas configuration \ more stable
