Ray;

I have posted this fully in another thread. This uses the Debye Huckle and the Nernst equations. They can be found here: http://en.wikipedia.org/wiki/Debye%E...Cckel_equation and here: http://en.wikipedia.org/wiki/Nernst_equation

This is a very laborious calculation from very complex equations. I hope it is of use to you.

PE