Question

Can the Nernst equation be expressed directly in terms of concentrations?

Answer 1

Yes, it can.

The Nernst equation is an expression that relates the cell potential of an electrochemical cell to the standard cell potential, temperature, and reaction quotient.

`E_"cell" = E_"cell"^° - (RT)/(zF)lnQ`

All we have to do is insert the expression for the reaction quotient.

For the cell reaction

aA + bB → cC + dD

`Q = frac{["C"]^c["D"]^d}{["A"]^a["B"]^b}`

So we can write the Nernst equation as

`E_"cell" = E_"cell"^° - (RT)/(zF)lnfrac{["C"]^c["D"]^d}{["A"]^a["B"]^b}`