JEE Main On 8 April 2017 Question 22
Question: What is the standard reduction potential $ (E{}^\circ ) $ for $ F{e^{3+}}\to Fe $ ? Given that: $ F{e^{2+}}+2{e^{-}}\to Fe;E^o _{F{e^{2+}}/Fe}=-0.47V $ $ F{e^{3+}}+{e^{-}}\to F{e^{2+}};E^o _{F{e^{3+}}/F{e^{2+}}}=+0.77V $ [JEE Online 08-04-2017]
Options:
A) -0.057 V
B) + 0.30 V
C) - 0.30 V
D) + 0.057 V
Show Answer
Answer:
Correct Answer: A
Solution:
$ E^{0} _{\frac{Fe^{3+}}{Fe}}=\frac{E^{0} _{\frac{Fe^{3+}}{Fe^{2+}}}+2\times E^{0} _{\frac{Fe^{2+}}{Fe}}}{3}$
Here, 1, 2 and 3 represents number of electrons that participate in respective half reactions.
