The voltage generated by the zinc concentration cell described by the line notation zn(s) ∣∣ zn2+(aq,0.100 m) ∥∥ zn2+(aq,? m) ∣∣ zn(s) is 14.0 mv at 25 °c. calculate the concentration of the zn2+(aq) ion at the cathode.

Respuesta :

Answer: The concentration of [tex]Zn^{2+}[/tex] ion at cathode is 0.295 M

Explanation:

The half reactions for the cell is:

Oxidation half reaction (anode):  [tex]Zn(s)\rightarrow Zn^{2+}(0.100M,aq.)+2e^-[/tex]

Reduction half reaction (cathode):  [tex]Zn^{2+}(?M,aq.)+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+}]_{anode}}{[Zn^{2+}]_{cathode}}[/tex]

where,

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

[tex]E_{cell}[/tex] = 14.0 mV = 0.014 V    (Conversion factor:  1 V = 1000 mV)

[tex][Zn^{2+}]_{anode}[/tex] = 0.100 M

[tex][Zn^{2+}]_{cathode}[/tex] = ? M

Putting values in above equation, we get:

[tex]0.014=0-\frac{0.0592}{2}\log \frac{0.100M}{[Zn^{2+}]_{cathode}}[/tex]

[tex][Zn^{2+}]_{cathode}=0.295M[/tex]

Hence, the concentration of [tex]Zn^{2+}[/tex] ion at cathode is 0.295 M

The concentration of Zn²⁺  ion at cathode is 0.295 M

Redox half equations

The redox half equations are those of oxidation and reduction

Oxidation half reaction: Zn(s) ---> Zn²⁺ + 2 e⁻ [Zn⁺] = 0.100 M

reduction half reaction: Zn²⁺ (aq) + 2 e⁻ ----> Zn (s)  [Zn⁺] = y

The Ecell = 14.0mV = 0.014 V

Using the Nernst equation:

  • Ecell = E°cell - 0.0592/n * log([Zn⁺]anode/[Zn⁺]cathode)
  • since it is a concentration cell, E°cell = 0

where n is number moles; n = 2

0.014 =  0 - 0.0592/2 * log (0.1/y)

y = 0.295 M

Therefore, the concentration of Zn²⁺  ion at cathode is 0.295 M

Learn more about concentration cells at: https://brainly.com/question/15394851

Q&A Education