what is the standard reduction potential?

Question

A galvanic cell consists of a Sn²⁺/Sn half-cell and a standard hydrogen electrode. If the Sn²⁺/Sn half-cell standard cell functions as the anode, and the standard cell potential is 0.14 V, what is the standard reduction potential for the Sn²⁺/Sn half-cell?

Answer 1

The question says that the cell is a galvanic cell therefore the E of the cell has to be a positive number.

The equation for the E of a cell is this:

Ecell = Ered - Eoxi

The question also says that Sn²⁺/Sn is the anode, which means that it produces electrons as part of the product for the redox reaction so it looks like this:

Sn —> 2e^- + Sn²⁺

Oxidation always occurs at the anode end a cell and this is what we will solve for, but we first have to figure out what the Reduced part of the cell is.

The question says that Hydrogen is the other part of the cell that is an electrode. So that part of the reaction looks like this and has a voltage of 0.

2H⁺ + 2e^-—> H₂

Now that we know the volatile of the cell (given in the question) and we know the voltage of the red part of the cell we can solve for the voltage of the oxidized part of the cell (which is the Sn²⁺/Sn part).

Ecell = Ered - Eoxi

0.14 = 0 - Eoxi

Solving for Eoxi gives us -0.14, which is the voltage for the Sn²⁺/Sn part of the reaction.