JEE PYQ: Electrochemistry Question 31
Question 31 - 2019 (12 Apr Shift 1)
Given: $\text{Co}^{3+} + e^- \rightarrow \text{Co}^{2+}$; $E^0 = +1.81$ V $\text{Pb}^{4+} + 2e^- \rightarrow \text{Pb}^{2+}$; $E^0 = +1.67$ V $\text{Ce}^{4+} + e^- \rightarrow \text{Ce}^{3+}$; $E^0 = +1.61$ V $\text{Bi}^{3+} + 3e^- \rightarrow \text{Bi}$; $E^0 = +0.20$ V
Oxidizing power of the species will increase in the order:
(1) $\text{Ce}^{4+} < \text{Pb}^{4+} < \text{Bi}^{3+} < \text{Co}^{3+}$
(2) $\text{Bi}^{3+} < \text{Ce}^{4+} < \text{Pb}^{4+} < \text{Co}^{3+}$
(3) $\text{Co}^{3+} < \text{Ce}^{4+} < \text{Bi}^{3+} < \text{Pb}^{4+}$
(4) $\text{Co}^{3+} < \text{Pb}^{4+} < \text{Ce}^{4+} < \text{Bi}^{3+}$
Show Answer
Answer: (2) $\text{Bi}^{3+} < \text{Ce}^{4+} < \text{Pb}^{4+} < \text{Co}^{3+}$
Solution
Higher reduction potential = higher oxidising power. Order: Bi$^{3+}$(0.20) < Ce$^{4+}$(1.61) < Pb$^{4+}$(1.67) < Co$^{3+}$(1.81).
BETA
