Which one of the following has a potential more than zero ?

Options

A. pt, `1/2 H_(2)` (1 atm) I HCl (1 M)
B. pt, `1/2 H_(2)` (1 atm) I HCl (2 M)
C. pt, `1/2 H_(2)` (1 atm) I HCl (0.1 M)
D. pt, `1/2 H_(2)` (1 atm) I HCl (0.5 M)

Answer

B

Explanation

For hydrogen electrode,
`E_(H^(+)"|"H_(2))=E_(H^(+)"|"H_(2))^(@)-(0.0591)/(n) log. (p_(H_(2)))/([H^(+)]^(@))`
(A) `E_(H^(+)"|"H_(2))=0-(0.0591)/(2) log. 1/1 = 0V`
(B) `E_(H^()"|"H_(2))=0-(0.0591)/(2) log. (1)/((2)^(2))=0.018V`
(C) `E_(H^(+)"|"H_(2))=0-(0.0591)/(2) log. (1)/((0.1)^(2))= -0.0591V`
(D) `E_(H^(+)"|"H_(2))=0-(0.0591)/(2) log. (1)/((0.5)^(2))= -0.018V`
Correct answer is (B)