Preferred Label : acidity function;
IUPAC definition : Any function that measures the thermodynamic hydron-donating or -accepting ability
of a solvent system, or a closely related thermodynamic property, such as the tendency
of the lyate ion of the solvent system to form Lewis adduct. (The term 'basicity function'
is not in common use in connection with basic solutions.) Acidity functions are not
unique properties of the solvent system alone, but depend on the solute (or family
of closely related solutes) with respect to which the thermodynamic tendency is measured.
Commonly used acidity functions refer to concentrated acidic or basic solutions. acidity
functions are usually established over a range of composition of such a system by
UV/VIS spectrophotometric or NMR measurements of the degree of hydronation (protonation
or Lewis adduct formation) for the members of a series of structurally similar indicator
bases (or acids) of different strength: the best known of these functions is the Hammett
acidity function H0 (for uncharged indicator bases that are primary aromatic amines).;
Origin ID : A00081;
See also
Any function that measures the thermodynamic hydron-donating or -accepting ability
of a solvent system, or a closely related thermodynamic property, such as the tendency
of the lyate ion of the solvent system to form Lewis adduct. (The term 'basicity function'
is not in common use in connection with basic solutions.) Acidity functions are not
unique properties of the solvent system alone, but depend on the solute (or family
of closely related solutes) with respect to which the thermodynamic tendency is measured.
Commonly used acidity functions refer to concentrated acidic or basic solutions. acidity
functions are usually established over a range of composition of such a system by
UV/VIS spectrophotometric or NMR measurements of the degree of hydronation (protonation
or Lewis adduct formation) for the members of a series of structurally similar indicator
bases (or acids) of different strength: the best known of these functions is the Hammett
acidity function H0 (for uncharged indicator bases that are primary aromatic amines).
