Question

The reduction potential of hydrogen half-cell will be negative, if :

• A. p(H2) = 1 atm and [H+] = 2.0 M
• B. p(H2) = 1 atm and [H+] = 1.0 M
• C. p(H2) = 2 atm and [H+] = 1.0 M
• D. p(H2) = 2 atm and [H+] = 2.0 M

Answer 1

Answer: (C)

p(H2) = 2 atm and $H+$ = 1.0 M

Answer 2

$\text{2}\text{H}^{+}\ (\text{aq})\text{ + 2}\text{e}^{-}\overset{\quad\quad}{\rightarrow}H_{2}\ (g)$

$\mathrm { E } _ { \text {red } } = \mathrm { E } _ { \text {rod } } ^ { 0 } - \frac { 0.0591 } { \mathrm { n } } \log \frac { \mathrm { P } _ { \mathrm { H } _ { 2 } } } { \left( \mathrm { H } ^ { + } \right) ^ { 2 } } ; \quad \mathrm { E } _ { \text {rod } } = 0 - \frac { 0.0591 } { 2 } \log \frac { 2 } { ( 1 ) ^ { 2 } } ;$ $\mathrm { E } _ { \text {red } } = - \frac { 0.0591 } { 2 } \log 2$ $E_{\text{red}}$is forund to be negative for (3) option.