Redox Reactions And Electrochemistry Ques 225
Question: The $ E^0_{{M^{3+}}/{M^{2+}}} $ values for $ Cr,\ Mn,\ Fe $ and $ Co $ are $ -0.41,\ +1.57,\ +0.77 $ and $ +1.97\ V $ respectively. For which one of these metals the change in oxidation state from $ +2 $ to $ +3 $ is easiest [AIEEE 2004]
Options:
A) $ Fe $
B) Mn
C) Cr
D) Co
Show Answer
Answer:
Correct Answer: C
Solution:
Reduction $ E_0{M^{3+}}/{M^{2+}} $ Cell reaction $ E_0{M^{2+}}/{M^{3+}} $ (Oxidation)
- .41 V $ C{r^{2+}} $ $ C{r^{3+}} $ + . 41 V
- 1.57 V $ M{n^{2+}} $ $ M{n^{3+}} $ - 1.57 V
- 0.77 V $ F{e^{2+}} $ $ F{e^{3+}} $ - 0.77 V
- 1.97 V $ C{o^{2+}} $ $ C{o^{3+}} $ - 1.97 V As $ Cr $ has maximum oxidation potential value, therefore its oxidation should be easiest.
