Hi (sorry if my english isn't good)

I have a task with which goes like this: 

A battery is based on oxidation of Magnesium and reduction of Copper-ions. The starting consentration of Mg²⁺-ions and Cu²⁺-ions are 1,0 * 10^-4 M and 1,5 M. The volume of each halfcell is 1 liter. 

a ) Calculate the battery-voltage at the start. 

b) Calculate the battery-voltage after the battery has delivered 5,0 A for 8,0 hours.   

 

I think i got a) right. I just calculated the cellpotential and put it in Nernst forumla like this: 

Oxidation: Mg²⁺ + 2e^-  --> Mg(s)      : -2.36V

Reduction: 2Cu²⁺ + 2e^- --> 2Cu       : 0.16 V

Cell potential: E = 0.16 - (-2.36) = 2,52 V

E_cell  = 2,52 V - (0,0592 V / 2 ) * log([1,5 M] / 2*[1,0 * 10^-4 M]) = 2,4053 V = 2,4 V        

 

My problem is b). I tried different ways to solve it but i can't figure it out. I suspect i have to use Faraday's forumal: n_p = (I * t) / (F * n), but i can't figure out how to use it to find the battery-potensial. 

Can anyone help me?

 

Sorry for but terrible translation xD

Edited April 21, 20205 yr by nassas91
typo

I'm not sure whether this is related to the problem you're having, but your oxidation looks to me like an reduction. The magnesium is capturing electrons.