## Homework Question

$\Delta G^{\circ} = -nFE_{cell}^{\circ}$

Moderators: Chem_Mod, Chem_Admin

305113590
Posts: 66
Joined: Fri Sep 28, 2018 12:28 am

### Homework Question

What range in volts does a voltmeter need to have to measure pH in the range of 1 to 14 at 25 Celsius if the voltage is zero when pH is 7?

I understand everything for the most part, but can anyone explain to me why we have to do this:

.025693ln(0.1/1x10^-13)= 0.710V
.025693ln(1x10^-14/1.0)=-0.828V

Why is do we have those values for lnK? Why specifically 1x10^-13 and 1.0?

Chem_Mod
Posts: 17839
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 406 times

### Re: Homework Question

1 x 10–13 is the concentration of OH(aq) at a pH of 1, and 1.0 is [OH] at pH 14.

Chem_Mod
Posts: 17839
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 406 times

### Re: Homework Question

On closer inspection, this appears to be a mistake. Use $E_{cell} = E_{cell}' + \frac{RT}{F} ln [H^+]$

Return to “Work, Gibbs Free Energy, Cell (Redox) Potentials”

### Who is online

Users browsing this forum: No registered users and 2 guests