The question says: Calculate the standard e.m.f. of the cell at 298 K? 1) Ni (s) | Ni 2+^ (aq)|| Sn 2+^ (aq), Sn 4+^ (aq) |pt ..... Will I have to use the Nernst equation? The questi does not even state if its standard or non standard? do i ignore the 298 K?? Please Register or Log in to view the hidden image!Please Register or Log in to view the hidden image!Please Register or Log in to view the hidden image!

Are you aware you have to calculate the reduction and oxidation? For instance, you would have \(E_0=E_{red}+E_{oxi}\) and will measure the voltage of the cell.

yes I know I need to calculate E cell which is E cathode - E anode I'm not entirely sure of the next steps I must take alltogether and how? Please could you guide me on this? thanks

Well, this is never easy stuff - atleast I never found it very easy. I even had to look it up again: here is an example: \(Zn(s) + Fe^2+ -----> Zn^2+ + Fe(s)\) To calculate the cell voltage, you need to split the equation (hopefully your are aware of how to do this, which gives us: \(Zn(s) -----> Zn2+ + 2e\) \(Fe^2+ +2e -----> Fe(s)\) Which are the two half-reactions as we have gathered you know about. You need to know the potentials required, so \( Zn^2+ + 2e -----> Z^n\) where \(E_0 = -0.76V\) This equation needs to be reversed, so \(E_0\) will be reversed also. \(Zn(s) -----> Zn^2+ + 2e\) \(E_0 = +0.76V\) \(Fe^2+ +2e -----> Fe(s)\) \(E_0 = -0.41V\) You then add the two equations together. ps. this is just an example. You will need to work this out yourself.

298K is a standard temperature so the question is about standard potentials. Pt is a standard "inert" electrode too--it doesn't get reduced or oxidized, but acts as a source or sink of electrons. Your answer might be found here

The Wiki page I referenced has a link to a list of standard electrode potentials, which will probably also be useful. These are often located in Chemistry textbooks, in the chapters that cover electrochemistry.