The Nemst equation is one of the most important equations in electrochemistry. T

Question

The Nemst equation is one of the most important equations in electrochemistry. To calculate the cell potential at non-standard-state conditions, the equation is E = E degree - 2.303RT/nF log10Q where E is the potential in volts. E degree is the standard potential in volts. R is the gas constant, T is the temperature in kelvins, n is the number of moles of electrons transferred. F is the Faraday constant, and Q is the reaction quotient. At standard temperature. 25 degree C or 298 K. the equation has the form E = E degree - (0.0592/n)logQ The reaction quotient has the usual form A table of standard reduction potentials gives the voltage at standard conditions. 1. OO M for all solutions and 1.00 atm for all gases. The Nemst equation allows for the calculation of the cell potential E at other conditions of concentration and pressure. For the reaction 2Co3+ (aq) + 2CI (aq) rightarrow 2Co2+ (aq) + Cl2(g). E degree = 0.71 V what is the cell potential at 25 degree C if the concentrations are [Co3+] = 0.102M. [Co2' ] = 0.756M. and [Cl ] = 0.640M and the pressure of Cl2 is Pci2 = 7.30atm ? Express your answer with the appropriate units.

Explanation / Answer

2Co32- + 2Cl- --> 2Co2+ cl2

Ecell = E0 -RT/2F ln[ Co2-]2/ [Cl-]2

AT 25 C,

IT BECOMES

Ecell= 0.059/2 * ln [ Co2-]2/ [Cl-]

E0 =0.71

[Co2-] =0.102 M

[Cl-]= 0.640

on substituting all the values,

0.71-(-3.67)

=4.38 V

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