Cell potentials, Ecell

Definition

Cell potential, denoted as $E_{cell}$, is the measure of the electromotive force (emf) of an electrochemical cell. It represents the potential difference between the two electrodes.

5 Must Know Facts For Your Next Test

1. The standard cell potential ($E^\circ_{cell}$) is measured under standard conditions: 1 M concentration for solutions, 1 atm pressure for gases, and 25°C.
2. Cell potential can be calculated using the Nernst equation when conditions are not standard.
3. $E_{cell}$ is positive for spontaneous reactions and negative for non-spontaneous reactions.
4. The overall cell potential is the difference between the reduction potentials of the cathode and anode: $E_{cell} = E_{cathode} - E_{anode}$.
5. A galvanic (voltaic) cell operates with a positive $E_{cell}$, while an electrolytic cell operates with a negative $E_{cell}$.

Review Questions

Related terms

Electrode Potential:

The voltage developed by a half-cell in an electrochemical cell relative to a standard reference electrode.

Nernst Equation:

An equation that relates the cell potential to its standard potential and concentrations of reactants and products: $$E = E^\circ - \frac{RT}{nF} \ln Q$$.

Galvanic Cell:

An electrochemical cell that derives electrical energy from spontaneous redox reactions occurring within the cell.