Electrochemistry – Chapter 21 Vocabulary

These vocabulary flashcards summarize the key electrochemistry concepts, equations, devices, and industrial processes presented throughout the Chapter 21 lecture notes.

Electrochemistry

The study of chemical reactions that produce electricity and of chemical changes driven by an electric current.

Electrochemical Cell

A device that converts chemical energy to electrical energy or vice-versa by means of redox reactions.

Galvanic (Voltaic) Cell

An electrochemical cell in which a spontaneous redox reaction generates electrical energy (Ecell > 0).

Electrolytic Cell

An electrochemical cell that uses external electrical energy to drive a non-spontaneous redox reaction (Ecell < 0).

Redox Reaction

A reaction involving the transfer of electrons from one species (oxidation) to another (reduction).

Oxidation

Loss of electrons; occurs at the anode of an electrochemical cell.

Reduction

Gain of electrons; occurs at the cathode of an electrochemical cell.

Oxidizing Agent

The species that is reduced and therefore gains electrons in a redox reaction.

Reducing Agent

The species that is oxidized and therefore loses electrons in a redox reaction.

Anode

Electrode where oxidation occurs; negative in a voltaic cell, positive in an electrolytic cell.

Cathode

Electrode where reduction occurs; positive in a voltaic cell, negative in an electrolytic cell.

Salt Bridge

A tube or porous plug that connects the half-cells of a galvanic cell, allowing ion flow to maintain charge balance.

Cell Notation

Shorthand representation of a galvanic cell: anode | anode solution || cathode solution | cathode.

Half-Reaction Method

Balancing technique that separates an overall redox equation into oxidation and reduction half-reactions, balances each for mass and charge, then recombines them.

Standard Hydrogen Electrode (SHE)

Reference electrode assigned a potential of 0.00 V, consisting of H2(g, 1 atm) bubbled over a Pt electrode in 1 M H+.

Standard Electrode Potential (E°)

The reduction potential of a half-reaction measured relative to the SHE under standard conditions (1 M, 1 atm, 25 °C).

Faraday Constant (F)

The charge of one mole of electrons, 96 485 C mol⁻¹ (≈9.65 × 10⁴ C mol⁻¹).

Concentration Cell

A galvanic cell in which the electrodes are identical but the ion concentrations differ; voltage arises from concentration gradient.

Activity Series (Reactivity of Metals)

Ranking of metals based on their ability to displace H₂ or other metals; derived from standard potentials.

Overvoltage (Overpotential)

Extra potential (≈0.4–0.6 V for water) required to overcome kinetic barriers in electrolysis reactions.

Electrolysis

The use of electrical energy to drive a non-spontaneous chemical reaction in an electrolytic cell.

Electroplating

Deposition of a metal coating on an object (cathode) via reduction of its ions during electrolysis.

pH Meter

Instrument that measures solution acidity by converting the voltage between a glass electrode and reference electrode (via the Nernst equation) into pH.

Ion-Selective Electrode

Electrode designed to develop a potential proportional to the concentration of a specific ion (e.g., F⁻, NO₃⁻, K⁺).

Free Energy of Reaction (ΔG)

Thermodynamic quantity indicating spontaneity; negative ΔG corresponds to positive Ecell for electrochemical reactions.