Q. Cerric ammonium sulphate and potassium permanganate are used as oxidising agents in acidic medium for oxidation of ferrous ammonium sulphate to ferric sulpahte. The ratio of number of moles of cerric ammonium sulphate required per mole of ferrous ammonium sulphate to the number of moles of ${KMnO}_{4}$ required per mole of ferrous ammonium sulphate, is
A) 5.0
B) 0.2
C) 0.6
D) 2.0
Explanation
(a)
${Fe}^{2 +} + {Ce}^{4 +}\ \longrightarrow {Fe}^{3 +} + {Ce}^{3 +}$
$5{Fe}^{2 +} + {MnO}_{4}^{-} + 8H^{+} \longrightarrow 5{Fe}^{3 +} + {Mn}^{2 +} + 4H_{2}O$
$\therefore\frac{Moles\ of\ cerric\ ammonium\ sulphate}{Moles\ of\ potassium\ permanganate} = \frac{1}{1/5} = 5.0\$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.