When an ion‑selective electrode for X+ was immersed in 0.0482 M XCl, the measured potential was 0.0460 V . What is the concentration of X+ when the potential is 0.0610 V ? Assume that the electrode follows the Nernst equation, the temperature is at 25 °C, and that the activity coefficient of X+ is 1.

Respuesta :

Answer : The concentration of [tex]X^+[/tex] is 0.0861 M

Explanation :

First we have to calculate the standard electrode potential of the cell.

Using Nernest equation :

[tex]E_{cell}=E^o_{cell}-\frac{2.303RT}{nF}\log \frac{1}{[X]}[/tex]

where,

F = Faraday constant = 96500 C

R = gas constant = 8.314 J/mol.K

T = room temperature = [tex]25^oC=273+25=298K[/tex]

n = number of electrons in oxidation-reduction reaction = 1

[tex]E^o_{cell}[/tex] = standard electrode potential of the cell = ?

[tex]E_{cell}[/tex] = emf of the cell = 0.0460 V

[X] = concentration = 0.0482 M

Now put all the given values in the above equation, we get:

[tex]0.0460=E^o_{cell}-\frac{2.303\times (8.314)\times (298)}{1\times 96500}\log \frac{1}{0.0482}[/tex]

[tex]E^o_{cell}=0.124V[/tex]

Now we have to calculate the concentration of [tex]X^+[/tex] when the potential is 0.0610 V.

Using Nernest equation :

[tex]E_{cell}=E^o_{cell}-\frac{2.303RT}{nF}\log \frac{1}{[X]}[/tex]

[tex]0.0610=0.124-\frac{2.303\times (8.314)\times (298)}{1\times 96500}\log \frac{1}{[X]}[/tex]

[tex][X]=0.0861M[/tex]

Therefore, the concentration of [tex]X^+[/tex] is 0.0861 M