Redox Reactions And Electrochemistry Ques 735
Question: The standard electrode potential for the following reaction is +1.33V. What is the potential at $ pH=2.0 $ - $ Cr_2O_7^{2-}(aq.1M)+14,{H^{+}}(aq)+6{e^{-}}\xrightarrow{{}} $ $ 2C{r^{3+}}(aq.,1,M)+7H_2O(\ell ) $
Options:
A) +1.820 V
B) +1.990 V
C) +1.608 V
D) +1.0542 V
Show Answer
Answer:
Correct Answer: D
Solution:
[d] $ {E _{Cr_2O_7^{2-}{{| Cr .}^{3+}}}}=E{{{}^\circ } _{Cr_2O_7^{2-}{{| Cr .}^{3+}}}},-\frac{0.0591}{6} $ $ \times ( \log \frac{{{[C{r^{3+}}]}^{2}}}{[Cr_2O_7^{2-}]}\times \frac{1}{{{[{H^{+}}]}^{14}}} ) $
$ {E _{Cr_2O_7^{2-}{{| Cr .}^{3+}}}}=1.33-\frac{0.0591}{6}\log \frac{1}{{{(0.01)}^{14}}} $
$ \Rightarrow $ $ 1.0542,V $
