[Rutherford]

I have some difficulties to understand few thing here.
1.Nernst equation:E=E^o+2.3RT/Fz*log[Ox]/[Red.]
a)Is the other simbol for E varphi?
b)What is [Ox] and what is [Red.], I found that they are the concentrations of the substances that take part in oxidation or reduction process, so why in the reaction:
Zn²⁺+2e^- Zn, is [Ox]=[Zn²⁺] when Zn²⁺ gets reduced, so it takes part in the process of reduction?

2.If I use Pt electrodes for a el. cell (for example, Zn and Ag solutions):
a)If Ag⁺ gets reduced where from does it get the electron when Pt is inert
b)How does Zn drop 2 electrons if all Zn is presented as Zn²⁺?
Do these have some connection with the bridge?

[Borek]

Is the other simbol for E varphi?

Huh?

What is [Ox]

Concentration of the oxidized specie.

If Ag⁺ gets reduced where from does it get the electron when Pt is inert

Pt is a just a conductor. You can't have just Ag⁺ reduced, it requires other half cell where something gets oxidized. It doesn't have to be in the same solution, but you have to allow charge transfer to close the circuit.

[Rutherford]

Concentration of the oxidized specie.

That explains why H⁺ is [Ox], too. I suppose that H₂ is [Red.] then, and Zn not because it is solid.

I meant 2 different solution (a cell, Ag and Zn with the salt bridge), Zn gets oxidized and Ag gets reduced, but I don't understand how Zn gets oxidized if all Zn in the solution is present as Zn²⁺ it can't lose any more electrons. Where from does Ag⁺ get electrons so it gets reduced?

[Olympiad_Tutor]

Zn   -2e -> Zn²⁺
Ag⁺   +e -> Ag

[Rutherford]

I don't understand where Zn comes from. There are only Zn²⁺ ions in the solution.
Where does the ecletron in the Ag⁺ solution come from?

[Borek]

If there is no metallic Zn there will be no reaction taking place. As you correctly spotted, for redox reaction you need both reducing and oxidizing agent at the same time, otherwise there is either no source of electrons or no electron sink.

[Rutherford]

So, on the anode and the cathode there should be a thin layer of Zn and Ag respectively so there will be made an equilibrium (in both half-cells) with the ions in the solution?