Fundamentals of Electrochemistry

Vocabulary terms and definitions covering the fundamentals of electrochemistry, cell types, redox balancing, and thermodynamic relationships.

Electrochemistry

The branch of chemistry that deals with the interconversion of electrical energy and chemical energy.

Electrochemical cell

A system consisting of electrodes that dip into an electrolyte and in which a chemical reaction either uses or generates an electric current.

Voltaic (galvanic) cell

An electrochemical cell in which a spontaneous reaction generates an electric current.

Electrolytic cell

An electrochemical cell in which an electric current drives an otherwise nonspontaneous reaction.

Anode

The electrode at which oxidation occurs; in shorthand notation, it is represented on the left side.

Cathode

The electrode at which reduction occurs; in shorthand notation, it is represented on the right side.

Salt bridge

A tube containing an electrolyte in a gel connected to two half-cells that allows the flow of ions but prevents the mixing of different solutions.

Standard state

A condition in an experiment where the concentration of solutions is $1.0\,M$ and the pressure of gases is $1.0\,atm$.

Oxidation number

The charge of an atom (in a free state or in a molecule) if electrons around it were completely transferred, rather than shared.

Oxidation-reduction (redox) reactions

Reactions where electrons are transferred from one species to another through simultaneous reduction and oxidation processes.

Reduction

Reactions where electrons are gained by the species.

Oxidation

Reactions where electrons are given off by the species.

OIL RIG

A mnemonic for redox reactions standing for Oxidation Is Loss, Reduction Is Gain.

Cell potential ($E_{cell}$)

A measure of the driving force or electromotive force (emf) of the cell reaction, measured in Volts.

Faraday constant ($F$)

A constant used in electrochemical calculations, valued at $96485\,C/mol\,e^-$.

Nernst Equation

An equation used to measure cell potential for non-standard solutions: $E_{cell} = E_{cell}^\circ - \frac{RT}{nF} \ln Q$.

Standard Free Energy Change ($\Delta G^\circ$)

The change in free energy under standard conditions, calculated as $\Delta G^\circ = -nFE_{cell}^\circ$.

Equilibrium Constant ($K$)

A value related to the standard free energy change by the equation $\Delta G^\circ = -RT \ln K$.