Electrochemistry & Redox — 60 Terms Defined

Redox Couple Electrochemistry & Redox V The oxidised and reduced forms of the same species, considered together as a conjugate pair. Ox / Red

Reducing Agent Electrochemistry & Redox V A species that donates electrons to another substance and is itself oxidised in the process.

Reduction Electrochemistry & Redox Dimensionless The gain of electrons by a species, accompanied by a decrease in its oxidation number. Xⁿ⁺ + n e⁻ → X

Reference Electrode Electrochemistry & Redox V A half-cell with a stable, known and reproducible potential, used as a fixed point against which other potentials are measured.

Rusting Electrochemistry & Redox Dimensionless The corrosion of iron in the presence of both oxygen and water to form hydrated iron(III) oxide. 4Fe + 3O₂ + 2xH₂O → 2Fe₂O₃·xH₂O

Sacrificial Anode Electrochemistry & Redox Dimensionless A block of reactive metal attached to a structure so that it corrodes preferentially and protects the structure.

Salt Bridge Electrochemistry & Redox Dimensionless A conducting connection between the two half-cells of a galvanic cell that completes the circuit and maintains electrical neutrality.

Secondary Cell Electrochemistry & Redox V A cell whose reaction can be reversed by an applied current, allowing it to be recharged and reused.

Selective Discharge Electrochemistry & Redox V The preferential reaction of one ion over others at an electrode during electrolysis.

Standard Electrode Potential Electrochemistry & Redox V The potential of a half-cell measured against the standard hydrogen electrode under standard conditions. E° at 298 K, 1 M, 1 bar

Standard Hydrogen Electrode Electrochemistry & Redox V The reference half-cell, consisting of hydrogen gas at 1 bar bubbled over platinum in 1 M acid, assigned a potential of exactly zero. 2H⁺ + 2e⁻ ⇌ H₂, E° = 0.00 V

Transport Number Electrochemistry & Redox Dimensionless The fraction of the total current carried by a particular ion in an electrolyte solution. t₊ = λ₊ / (λ₊ + λ₋)