Question

Use the Nernst equation to calculate the theoretical value of E of th copper-concentration cell and compare this value with th cell potential you measured.

E = E* - 0.0592 / n * logQ

**So I believe this is the equation that I would use. However, i'm don't know what E* is suppose to be...**

The my electrochemistry experiment the cell potential that i measured were: 0.130V, 0.115V, and 0.110V (average cell potential = 0.118V)

The concentration of the copper concentration cells used for this lab were: 0.05M CuSO₄ and 1.0M CuSO₄

standard reduction potential (in text) = Cu²⁺ + 2e^- --> Cu(s) E* = +0.34V **I believe I use the 2 here for n in the Nernst equation. **

am i doing this right? ---> E= 0.118v - 0.0592V / 2e^- * log (1.0M/0.05M) =0.0795V ???

Answer 1

Concepts and reason

Electrochemical cell is an experimental setup, which is used to generate the electrical energy from the spontaneous chemical reaction (Galvanic cells) or used to drive a non-spontaneous reaction by using external electrical energy (Electrolytic cells). Therefore, electrochemical cells are classified into two major types.

Standard cell potential: The potential of the cell under standard reaction conditions is known as the cell’s potential in standard state. The standard state conditions are concentration and pressure at any temperature. Species that have higher value of reduction potential undergo a reduction reaction, while species with lower value of reduction potential undergo an oxidation reaction. The oxidation takes place at the anode and the reduction reaction takes place at the cathode.

Concentration cell: A cell consisting of electrodes of same type, which has different concentration of ions, is known as concentration cell. The difference in the concentration of ions at anode and cathode affects the value of cell potential. The difference in ion concentration in different compartments leads to the formation of the concentration cell.

The standard electrode potential () for the material is the measure of the potential difference between the given material and standard hydrogen electrode (SHE) at standard temperature and pressure with the electrolyte concentration of.

Fundamentals

The standard cell potential value for a reaction is calculated as follows:

The relationship between cell potential and reaction quotient is described by the Nernst equation.

Here

is the cell potential.

is the standard cell potential.

is the number of electrons involved in the cell.

is the reaction quotient.

is the concentration of anode or oxidation.

is the concentration of cathode or reduction.

The data given in the problem is written as follows:

The standard reduction potential for the half-cell reaction of is .

The theoretical cell potential for the given cell is calculated as follows.

It is known that the standard cell potential for the concentration cell is zero.

Use the Nernst equation.

Substitute for , for , for and for as follows:

Therefore, the theoretical cell potential for the given cell is .

The measure cell potential for the copper concentration cell is .

The theoretical cell potential is much less than the actual value when compared with the values of cell potentials.

Ans:

The theoretical cell potential for the given cell is , which is less than the measured value.