What does an aqueous solution of a soluble salt mean? And what does it mean, in terms of electrochemistry, when the aqueous salt plates out as free, solid, metal?
actually in this case, it is as the slightly soluble salt.
Firstly, the reduction is the same for both reactions 1) and 2)
1) CuSO4 (aq) + Pb (s) goes to PbSO4 (s) + Cu (s)
2) Cu(NO3)2 (aq) + Pb(s) goes to Pb(NO3)2(aq) + Cu(s)
but for the anode
1) Pb (s) goes to PbSO4 (s)
2) Pb(s) goes to Pb(NO3)2(aq)
look up the reduction potentials for PbSO4(s) and Pb(NO3)2(aq)
I believe emf is just standard potential so it would be the reduction potential of the cathode minus the anode.
you should see the difference in the emf.