Question

For the reaction 2Co3+(aq)+2Cl−(aq)→2Co2+(aq)+Cl2(g). E∘=0.483 V what is the cell potential at 25 ∘C if the concentrations are [Co3+]= 0.456 M , [Co2+]= 0.451 M , and [Cl−]= 4.50×10−2 M and the pressure of Cl2 is PCl2= 2.30 atm ?

Answer 1

The cell potential at Non-Standard State conditions such as concentrations different than 1M can be calculated with the following formula:

In this case the Temperature remain at 25ºC which is standard temperature so the formula can be simplified:

Where:

Is the Cell potential at non-Standard state conditions

Is the Cell potential at Standard state conditions

Number of mole of electrons transferred in the balanced equation for the reaction

Reaction quotient which for the reaction aA + bB cC + dD can be calculated as:

The reaction equation is the following:

which can be alse written as following:

so the number of mol electrons transferred is of n=2

Then we calculate Q, we use the concentrations for liquids and the partial pressure for gases:

So the complete formula would see like this: