Chapter 9 - Electrochemistry

Electrochemistry

The study of chemical reactions in which electrons are transferred from one substance to another.

Oxidation

The loss of electrons during a chemical reaction, resulting in an increase in oxidation state.

Reduction

The gain of electrons during a chemical reaction, resulting in a decrease in oxidation state.

Oxidation State (Pure Elements)

The oxidation state for any atom in a pure element is defined as $0$.

Voltaic Cell

An electrochemical cell that produces electrical current from a spontaneous chemical reaction.

Electrolytic Cell

An electrochemical cell that consumes electrical current to drive a nonspontaneous chemical reaction.

Anode

The electrode in an electrochemical cell where oxidation occurs and from which electrons flow.

Cathode

The electrode in an electrochemical cell where reduction occurs and toward which electrons flow.

Salt Bridge

A device used to connect the oxidation and reduction half-cells while maintaining charge balance by allowing ions to flow.

Standard Electrode Potentials

The tendency of a half-reaction to lose or gain electrons under standard conditions, measured against the standard hydrogen electrode.

Standard Hydrogen Electrode

The reference electrode used for potential measurements, defined by the reaction $2H^+(aq) + 2e^- \rightarrow H_2(g)$ with an $E^Ș_{cathode} = 0.00\,V$.

Cell Potential ($E_{cell}$)

The potential energy difference between the anode and cathode that causes electrons to flow, producing an electrical current.

Standard Cell Potential ($E^Ș_{cell}$)

The cell potential measured under standard conditions, calculated as $E^Ș_{cell} = E^Ș_{cathode} - E^Ș_{anode}$.

Faraday’s Constant ($F$)

The magnitude of electrical charge per mole of electrons, equal to $96,485\,C/mol\,e^-$.

Volt ($V$)

A unit of potential difference defined as $1\,J/C$ (Joule per Coulomb).

Ampere ($Amp$)

A unit of electrical current defined as the rate of electron flow equal to $1\,C/s$ (Coulomb per second).

Free Energy Change ($\Delta G^Ș$)

The maximum amount of energy available to do useful work, related to cell potential by the equation $\Delta G^Ș = -nFE^Ș_{cell}$.

Nernst Equation