Electrochemistry & Redox — 60 Terms Defined

Electrorefining Electrochemistry & Redox Dimensionless The purification of a metal by dissolving it from an impure anode and depositing it in pure form at the cathode.

Electrowinning Electrochemistry & Redox kWh/kg The extraction of a metal from a solution or molten salt of its ore by electrolysis.

Faraday Constant Electrochemistry & Redox C/mol The electric charge carried by one mole of electrons. F = 96,485 C/mol

Faraday's First Law of Electrolysis Electrochemistry & Redox g The mass of a substance liberated at an electrode is directly proportional to the quantity of electricity passed. m = Z I t

Faraday's Second Law of Electrolysis Electrochemistry & Redox g When the same quantity of electricity passes through different electrolytes, the masses deposited are proportional to their chemical equivalent weights. m₁/m₂ = E₁/E₂

Free Energy and Cell Potential Electrochemistry & Redox kJ/mol The relation linking the Gibbs energy change of a cell reaction to the electromotive force it generates. ΔG = −nFE

Fuel Cell Electrochemistry & Redox V An electrochemical cell that generates electricity continuously from a fuel and oxidant supplied from outside.

Galvanic Cell Electrochemistry & Redox V An electrochemical cell in which a spontaneous redox reaction generates electrical energy. E°cell > 0

Galvanic Corrosion Electrochemistry & Redox mm/year Accelerated corrosion of the more reactive of two different metals in electrical contact within an electrolyte.

Galvanisation Electrochemistry & Redox μm The coating of iron or steel with a layer of zinc to protect it from corrosion.

Glass Electrode Electrochemistry & Redox V An ion-selective electrode whose thin glass membrane develops a potential proportional to the pH of the solution. E = constant − 0.0592 pH

Half-Reaction Electrochemistry & Redox Dimensionless An equation showing either the oxidation or the reduction part of a redox process, including the electrons transferred. Ox + n e⁻ ⇌ Red

Hydrogen–Oxygen Fuel Cell Electrochemistry & Redox V A fuel cell in which hydrogen is oxidised at the anode and oxygen reduced at the cathode, producing only water. 2H₂ + O₂ → 2H₂O, E° = 1.23 V

Kohlrausch's Law Electrochemistry & Redox S·cm²/mol At infinite dilution, the molar conductivity of an electrolyte is the sum of independent contributions from its cations and anions. Λ°m = ν₊λ°₊ + ν₋λ°₋

Lead–Acid Accumulator Electrochemistry & Redox V A rechargeable cell using lead and lead dioxide electrodes in sulfuric acid. Pb + PbO₂ + 2H₂SO₄ ⇌ 2PbSO₄ + 2H₂O

Limiting Molar Conductivity Electrochemistry & Redox S·cm²/mol The molar conductivity of an electrolyte extrapolated to infinite dilution, where ionic interactions vanish. Λ°m

Lithium-Ion Battery Electrochemistry & Redox V A rechargeable cell in which lithium ions shuttle between a graphite anode and a metal oxide cathode. LiCoO₂ + C₆ ⇌ Li₁₋ₓCoO₂ + LiₓC₆

Molar Conductivity Electrochemistry & Redox S·cm²/mol The conductivity of a solution divided by the molar concentration of the electrolyte. Λm = κ / c

Nernst Equation Electrochemistry & Redox V The equation relating a cell's potential to the concentrations of the species involved. E = E° − (RT/nF) ln Q

Overpotential Electrochemistry & Redox V The extra voltage beyond the theoretical value that must be applied before an electrode reaction proceeds at a useful rate. η = E_applied − E_equilibrium

Oxidation Electrochemistry & Redox Dimensionless The loss of electrons by a species, accompanied by an increase in its oxidation number. M → Mⁿ⁺ + n e⁻

Oxidation Number Electrochemistry & Redox Dimensionless The hypothetical charge an atom would carry if all its bonds were treated as fully ionic. Σ oxidation numbers = overall charge

Oxidising Agent Electrochemistry & Redox V A species that accepts electrons from another substance and is itself reduced in the process.

Primary Cell Electrochemistry & Redox V A cell in which the electrode reaction is irreversible, so it cannot be recharged.