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Question

Chemistry Question on Nernst Equation

The cell potential of the following cell at 25oC\text{25}{{\,}^{\text{o}}}\text{C} (in volts) is (pt)H2(1atm)H+(0.01M)Cu2+0.1MCu\underset{(1\,atm)}{\mathop{(pt){{H}_{2}}}}\,\left| \underset{(0.01M)}{\mathop{{{H}^{+}}}}\, \right|\left| \underset{0.1\,M}{\mathop{C{{u}^{2+}}}}\, \right|Cu (ECu2+Cuo=0.337V)(E_{C{{u}^{2+}}|Cu}^{o}=0.337\,V)

A

0.3080.308

B

0.4270.427

C

0.308-0.308

D

0.3370.337

Answer

0.4270.427

Explanation

Solution

(Pt)H2(1atm)H(0.01M)+Cu2+(0.1M)Cu\underset{(1\,atm)}{\mathop{(Pt){{H}_{2}}}}\,\left| {{\underset{(0.01\,M)}{\mathop{H}}\,}^{+}} \right|\left| \underset{(0.1\,M)}{\mathop{C{{u}^{2+}}}}\, \right|Cu For the above cell, the cell reaction is H2+Cu2+2H++Cu{{H}_{2}}+C{{u}^{2+}}\xrightarrow{{}}2{{H}^{+}}+Cu According to the Nemst equation Ecell=ECu2+/Cuo0.0591nlog[H+]2[Cu2+]{{E}_{cell}}=E_{C{{u}^{2+}}/Cu}^{o}-\frac{0.0591}{n}\log \frac{{{[{{H}^{+}}]}^{2}}}{[C{{u}^{2+}}]} =0.3370.05912log(0.01)2(0.1)=0.337-\frac{0.0591}{2}\log \frac{{{(0.01)}^{2}}}{(0.1)} =0.3370.02955log103=0.337-0.02955\log {{10}^{-3}} =0.337+0.08865=0.337+0.08865 =0.425650.427=0.42565\approx 0.427