electrochemistry

Electrochemistry

The study of chemical processes that cause electrons to move; energy is released by spontaneous reactions is converted to electricity and electrical energy is used to cause non-spontaneous reactions to occur.

Electrolytic Cell

Electrochemical cell that uses electrical energy to drive a non-spontaneous redox reaction; Requires energy to proceed.

Voltaic/Galvanic Cell

Electrochemical cell that converts chemical energy into electrical energy in a spontaneous redox reaction; Releases energy when proceeding;

Electrode

A conductor through which electricity enters or leaves an object, substance, or device.

Anode

The electrode where oxidation occurs; Loses electrons; Where electrons are released; Where current flows from.

Cathode

The electrode where reduction occurs; Gains electrons; Where electrons are gained; Where current flows to.

Oxidation

The loss of electrons or an increase in oxidation state by a molecule, atom, or ion.

Reduction

The gain of electrons or a decrease in oxidation state by a molecule, atom, or ion.

Oxidizing Agent

A substance that oxidizes another substance by accepting its electrons; Being reduced in the process.

Reducing Agent

A substance that reduces another substance by donating electrons; Being oxidized in the process.

Salt Bridge

A connection containing an electrolyte, that allows ion migration between the half cells, completing the circuit; usually a U-shaped tube that contains a gel permeated with a salt that is not part of the redox reaction.

Cell Potential

The measure of the potential difference between two half cells in an electrochemical cell; Related to the spontaneity of the redox reaction; Also known as voltage; E_{cell}; Measured in volts (V).

Standard Reduction Potential

The potential of a half-cell under standard conditions (1 M, 1 atm, 25°C) measured relative to the standard hydrogen electrode (SHE); E°, where the degree symbol indicates standard conditions.

Nernst Equation

An equation that relates the reduction potential of an electrochemical reaction to the standard electrode potential, temperature, and activities of the chemical species that are undergoing reduction and oxidation; E = E° - (RT/nF)lnQ, where R is the gas constant, T is the temperature, n is the number of moles of electrons transferred in the cell reaction, F is Faraday's constant, and Q is the reaction quotient.

Faraday's Constant

The amount of electric charge carried by one mole of electrons; Approximately 96485 \frac{Coulombs}{mol}; Represented by F.

Electrolysis

The process of using electrical energy to drive a non-spontaneous chemical reaction.

Overpotential

The potential difference between the thermodynamically predicted potential and the actual potential required for electrolysis to occur. It arises from kinetic barriers in the electrochemical process.

Corrosion

The process by which a metal is oxidized by substances in its environment, returning it to its more stable ionic state.

sacrificial anode

A more readily oxidized metal used to protect another metal from corrosion by being oxidized in its place