D-And F-Block Elements Ques 483
Question: Of Cr (VI) as $ Cr_2O{{_7^{2-}}^{~}} $ and $ CrO{{_4^{2-}}^{~}} $ , which is better oxidising agent-
Options:
A) $ CrO_4^{2-} $ , basic medium
B) $ Cr_2O_7^{2-} $ , basic medium
C) $ Cr_2O_7^{2-} $ , acidic medium
D) $ CrO_3 $ basic medium
Show Answer
Answer:
Correct Answer: C
Solution:
$ CrO_4^{2-}(aq)+4H_2O+3{{e}^{-}}\xrightarrow{{}} $ $ Cr{{( OH )}_3}+5O{{H}^{-}}, $ $ E{}^\circ =-0.13V $ $ Cr_2O_7^{2-}(aq.)+14{{H}^{+}}(aq.)+6{{e}^{-}}\xrightarrow{{}} $ $ 2C{{r}^{3+}}( aq. )+7H_2O, $ $ E{}^\circ =1.33V $
