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Ion-Selective Electrodes/finding pH

Posted: Wed Mar 15, 2017 11:42 pm
by Christina_F_3F
Hi,
I'm still a little bit confused on what ion selective electrodes are and how they relate to the Nernst equation.
I'm also not sure how the pH of a solution may be determined from the Nernst equation.
Basically, the top half of page 54 in the course reader, the section titled "Applications of e- transfer reactions" is not making sense to me.
If anyone could provide any sort of clarification on either of these two topics I would greatly appreciate it.
Thank you!

Re: Ion-Selective Electrodes/finding pH

Posted: Thu Mar 16, 2017 12:35 am
by Christian Hardoy 3F
An ion-selective electrode is a sensor that allows one to measure ionic concentrations in aqueous solution. If you've ever seen a pH meter that you stick into a solution in high school chemistry, for example, that would be a common example of an ion-selective electrode. It allows you to measure the concentration of hydronium or H+ ions to determine a solution's pH.

As for determining pH from the Nernst equation, I would think that that would be achieved by solving for the [P] or [R] of a particular reaction to determine the concentration of H+, or something like that.

Hope this helps!

Re: Ion-Selective Electrodes/finding pH

Posted: Thu Mar 16, 2017 1:14 am
by Christina_F_3F
It does -- thanks!