Acids, Bases & Salts — 11 Terms Defined

Acid Acids, Bases & Salts Dimensionless A substance that donates protons, produces hydrogen ions in water, or accepts a pair of electrons. HA → H⁺ + A⁻

Acid Dissociation Constant Acids, Bases & Salts mol/L The equilibrium constant for the ionisation of an acid in water, measuring its strength. Ka = [H⁺][A⁻] / [HA]

Acid Strength and Molecular Structure Acids, Bases & Salts Dimensionless The structural factors that determine how readily a molecule releases a proton.

Acidic Buffer Acids, Bases & Salts Dimensionless A buffer made from a weak acid and one of its salts, giving a pH below 7. pH = pKa + log([salt]/[acid])

Acidic Salt Acids, Bases & Salts Dimensionless A salt whose aqueous solution has a pH below 7, or one that still contains replaceable hydrogen.

Acidic Solution Acids, Bases & Salts mol/L A solution in which the hydrogen ion concentration exceeds the hydroxide ion concentration. [H⁺] > [OH⁻]

Acid–Base Indicator Acids, Bases & Salts Dimensionless A weak acid or base whose conjugate forms have distinctly different colours, used to signal the end point of a titration. HIn ⇌ H⁺ + In⁻

Acid–Base Titration Acids, Bases & Salts mol/L A titration in which an acid is neutralised by a base, or the reverse, monitored by an indicator or a pH meter. M_aV_a / n_a = M_bV_b / n_b

Amphiprotic Species Acids, Bases & Salts Dimensionless A species that can both donate and accept a proton.

Amphoteric Substance Acids, Bases & Salts Dimensionless A substance able to react as either an acid or a base depending on what it meets.

Arrhenius Theory Acids, Bases & Salts Dimensionless The theory defining an acid as a substance that produces H⁺ ions in water and a base as one that produces OH⁻ ions. HA → H⁺ + A⁻; BOH → B⁺ + OH⁻