[sebmista]

Ok - I remember when I took this in general chemistry but for some reason now its kickin' my ass.. Here are some questions I would like some help on if you guys dont mind.

So.. Ecell follows the basic equation :  Ecell = EnotCell - (.059/n) log(Keq)  Correct? And this is for half reactions

The total Ecell = Eright - Eleft ..

Now I get confused when I have to pick which half reaction is the right and which one is the left?

Appart from this I'm working on a question that goes like this.
--Consider the titration of 25mL of 0.01M Sn2+ by 0.05M TI3+ in 1M HCl, using Pt saturated calomel electrodes to fin the end point..

a) Write a balanced titration reaction
b)Write the nernst equation for the two different half reactions occurring at the indicator electrode.
c) Calculate E at the following volumes of TI3+ 4.90, 5.00 and 5.10mL

To be honest I'm like a deer in headlights i have no clue what to do.. I dont even know what its asking.. I'm usually good at chemistry I just recieved an A on my most recent Analytical Chemistry exam.. I just need someone to please explaine these things and I can then probably carry myself from there, PLEASE *delete me*

[FeLiXe]

when dealing with the Nernst equation I normally like to use

delta G = delta G° + RT ln Q

if you know how to use that equation you just have to put in

delta G = -n F Ecell

delta G° = -n F Enotcell

and you get the Nernst equation and you should know which way to plug values in

[sebmista]

Ok, I think I figured out how to do this problem...

First of all theres not a right or left cell, theres a Reaction ---
--The two half reactions are --

Tl³⁺ + 2e- = Tl⁺

Sn⁴⁺ + 2e- = Sn²⁺
---------------------
Now we need to react Sn²⁺ with Tl³⁺ so we have to add the top half reaction and subtract the bottom half reaction.. and after we do that we get

Rxn
Sn²⁺ + Tl³⁺ = Sn⁴⁺ + Tl⁺

This is the answer to part (a)

Now for part (b) we just do the two half reaction cell potentials
E_pt = 1.280 - (.059/2) log ([Tl⁺/Tl³⁺)
E_pt = .130 - (.059/2) log ([Sn²⁺/Sn⁴⁺)

For part (c) we just then add the Moles to the reaction in part (a) and then use the equations in part (b) with the new concentrations to find E cell...

[FeLiXe]

that should do it