A concentration cell is one in which both the anode and cathode are the same but with different concentrations. Calculate the cell potential with [Zn2+] = 0.10 M for the cathode and the [Zn2+] = 0.010 M for the anode?

A. + 0.06 V
B. - 0.03 V
C. + 0.03 V
D. 0.0 V

Respuesta :

Answer:

Cell potential is 0.03 V

Explanation:

Anode: [tex]Zn\rightarrow Zn^{2+}(0.01M)+2e^{-}[/tex]

Cathode: [tex]Zn^{2+}(0.10M)+2e^{-}\rightarrow Zn[/tex]

Overall: [tex]Zn^{2+}(0.10M)\rightarrow Zn^{2+}(0.01M)[/tex]

Nenrst equation for this cell reaction at [tex]25^{0}\textrm{C}[/tex]:

Cell potential, [tex]E_{cell}=\frac{-0.059}{n}log{\frac{[Zn^{2+}]_{0.01M}}{[Zn^{2+}]_{0.10M}}}[/tex]

Where n is number of electron exchanged

Here n=2

So, [tex]E_{cell}=\frac{-0.059}{2}log{\frac{0.01}{0.10}}=0.03V[/tex]

Answer: The cell potential of the cell is +0.03 V

Explanation:

The half reactions for the cell is:

Oxidation half reaction (anode):  [tex]Zn(s)\rightarrow Zn^{2+}+2e^-[/tex]

Reduction half reaction (cathode):  [tex]Zn^{2+}+2e^-\rightarrow Zn(s)[/tex]

In this case, the cathode and anode both are same. So, [tex]E^o_{cell}[/tex] will be equal to zero.

To calculate cell potential of the cell, we use the equation given by Nernst, which is:

[tex]E_{cell}=E^o_{cell}-\frac{0.0592}{n}\log \frac{[Zn^{2+}{diluted}}{[Zn^{2+}{concentrated}]}[/tex]

where,

n = number of electrons in oxidation-reduction reaction = 2

[tex]E_{cell}[/tex] = ?

[tex][Zn^{2+}{diluted}][/tex] = 0.010 M

[tex][Zn^{2+}{concentrated}][/tex] = 0.10 M

Putting values in above equation, we get:

[tex]E_{cell}=0-\frac{0.0592}{2}\log \frac{0.0101M}{0.10M}[/tex]

[tex]E_{cell}=0.03V[/tex]

Hence, the cell potential of the cell is +0.03 V

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