A Galvanic cell consists of Mg electrode in a 1.0 mol L -1 Mg(NO3)2 solution and a Ag electrode in a 1.0 mol L-1 AgNO3 solution. Calculate standard emf for the spontaneous reaction of this electrochemical cell at 25 C, given that the standard reduction potential Eo for Ag+ is +0.80 V and Eo for Mg2+ is -2.37 V.

Question

A Galvanic cell consists of Mg electrode in a 1.0 mol L -1 Mg(NO3)2 solution and a Ag electrode in a 1.0 mol L-1 AgNO3 solution.  Calculate standard emf for the spontaneous reaction of this electrochemical cell at 25 C, given that the standard reduction potential Eo for Ag+ is +0.80 V and Eo for Mg2+ is -2.37 V.

Answer is 3.17 V.

I know that Cathode - Annode = Eo cell
How can I find out which is the Cathode and Annode since this is written in a question and not in an equation.  The annode is usually on left of equation and cathode on right.

Thanks

Anonymous · Accepted Answer

A voltaic cell consist of a Mg electrode in 1.0 M Mg(NO3)2 and a Ag electrode in 1.0 M AgNO3. Calculate the standard cell potential at 25oC. Mg →Mg2+ +2e- Ag → Ag+ +e-

Aubree · Answer

The more positive reduction potential will always be the cathode. That is, Ag+ will be the cathode, and Mg2+ will be the anode.

Hakime · Answer

E°=-2.37-0.80 E°=-3.17