Gen Chem II Ch 18: Electrochemistry

Vocabulary flashcards based on electrochemistry lecture notes.

Redox Reaction

A reaction where one or more elements change oxidation number; always involves both oxidation and reduction.

Oxidation

The process that occurs when the oxidation number of an element increases, the element loses electrons, a compound adds oxygen, or a compound loses hydrogen.

Reduction

The process that occurs when the oxidation number of an element decreases, the element gains electrons, a compound loses oxygen, or a compound gains hydrogen.

Oxidizing Agent

The reactant molecule that causes oxidation; contains the element that is reduced.

Reducing Agent

The reactant molecule that causes reduction; contains the element that is oxidized.

Oxidation State

A number assigned to an element in a compound or ion that reflects the number of electrons lost or gained.

Electrochemical Cell

A device that converts chemical energy into electrical energy or vice versa through redox reactions.

Voltaic Cell

An electrochemical cell that uses spontaneous redox reactions to generate electricity; also known as a galvanic cell.

Electrolytic Cell

An electrochemical cell that uses electrical energy to drive nonspontaneous redox reactions.

Half-Cell

One half of an electrochemical cell where either oxidation or reduction takes place.

Electrode

A conductive solid (metal or graphite) that allows the transfer of electrons in an electrochemical cell.

Anode

The electrode where oxidation occurs; anions are attracted to it. Loses weight in an electrolytic cell.

Cathode

The electrode where reduction occurs; cations are attracted to it. Gains weight in an electrolytic cell.

Salt Bridge

A component of a voltaic cell that completes the circuit and maintains charge balance by allowing ion flow.

Electrical Current

The amount of electric charge that passes a point in a given period of time, whether as electrons flowing through a wire or ions flowing through a solution.

Ampere (A)

The unit of electrical current; 1 A = 1 Coulomb of charge flowing by each second.

Potential Difference

The difference in potential energy between the reactants and products; measured in volts.

Volt (V)

The unit of potential difference; 1 V = 1 J of energy/Coulomb of charge.

Cell Potential

The difference in potential energy between the anode and the cathode in a voltaic cell.

Standard EMF (E°cell)

The cell potential under standard conditions (25°C, 1 atm for gases, 1 M concentration of solution).

Electromotive Force (EMF)

The amount of force pushing the electrons through the wire.

Cell Notation

A shorthand description of a voltaic cell, showing the oxidation half-cell on the left and the reduction half-cell on the right.

Standard Hydrogen Electrode (SHE)

A standard half-reaction (reduction of H+ to H2) assigned a potential difference of 0 V, used as a reference for measuring other half-cell potentials.

Standard Reduction Potential

The potential of a half-cell under standard conditions, measured relative to the standard hydrogen electrode.

Nernst Equation

An equation used to calculate cell potential under nonstandard conditions, taking into account temperature and concentrations.