Cell Potentials and Gibbs' Free Energy

• The Nernst equation allows us to determine the cell potential at nonstandard-state conditions
• When Q <1

  [reactant] > [products]

  ln Q < 0

  so Ecell > Eo cell

  When the concentration of the reactants increases, the cell potential increases
• When Q =1

  [reactant] = [products]

  ln Q = 0

  so Ecell = E o cell

  When Q =1, the reaction is at equilibrium
• When Q >1

  [reactant] < [products]

  ln Q > 0

  so Ecell < Eo cell

  When the concentration of the product increases, the cell potential decreases
• A concentration cell is one in which the half-reactions are the same but the concentrations are different