Preferred Label : kinetic electrolyte effect;
Detailed label : kinetic electrolyte effect (kinetic ionic-strength effect);
IUPAC definition : The general effect of an added electrolyte (i.e. an effect other than, or in addition
to, that due to its possible involvement as a reactant or catalyst) on the observed
rate constant of a reaction in solution. At low concentrations (when only long-range
coulombic forces need to be considered) the effect on a given reaction is determined
only by the ionic strength of the solution and not by the chemical identity of the
ions. For practical purposes, this concentration range is roughly the same as the
region of validity of the Debye–Hückel limiting law for activity coefficients. At
higher concentrations, the effect of an added electrolyte depends also on the chemical
identity of the ions. Such specific action can usually be interpreted as the incursion
of a reaction path involving an ion of the electrolyte as reactant or catalyst, in
which case the action is not properly to be regarded just as a kinetic electrolyte
effect. Kinetic electrolyte effects are usually (too restrictively and therefore incorrectly)
referred to as 'kinetic salt effects'. A kinetic electrolyte effect ascribable solely
to the influence of the ionic strength on activity coefficients of ionic reactants
and transition states is called a 'primary kinetic electrolyte effect'. A kinetic
electrolyte effect arising from the influence of the ionic strength of the solution
upon the pre-equilibrium concentration of an ionic species that is involved in a subsequent
rate-limiting step of a reaction is called a 'secondary kinetic electrolyte effect'.
A common case encountered in practice is the effect on the concentration of hydrogen
ion (acting as catalyst) produced from the ionization of a weak acid in a buffer solution.
Synonymous with kinetic equivalence.;
Origin ID : K03401;
See also
The general effect of an added electrolyte (i.e. an effect other than, or in addition
to, that due to its possible involvement as a reactant or catalyst) on the observed
rate constant of a reaction in solution. At low concentrations (when only long-range
coulombic forces need to be considered) the effect on a given reaction is determined
only by the ionic strength of the solution and not by the chemical identity of the
ions. For practical purposes, this concentration range is roughly the same as the
region of validity of the Debye–Hückel limiting law for activity coefficients. At
higher concentrations, the effect of an added electrolyte depends also on the chemical
identity of the ions. Such specific action can usually be interpreted as the incursion
of a reaction path involving an ion of the electrolyte as reactant or catalyst, in
which case the action is not properly to be regarded just as a kinetic electrolyte
effect. Kinetic electrolyte effects are usually (too restrictively and therefore incorrectly)
referred to as 'kinetic salt effects'. A kinetic electrolyte effect ascribable solely
to the influence of the ionic strength on activity coefficients of ionic reactants
and transition states is called a 'primary kinetic electrolyte effect'. A kinetic
electrolyte effect arising from the influence of the ionic strength of the solution
upon the pre-equilibrium concentration of an ionic species that is involved in a subsequent
rate-limiting step of a reaction is called a 'secondary kinetic electrolyte effect'.
A common case encountered in practice is the effect on the concentration of hydrogen
ion (acting as catalyst) produced from the ionization of a weak acid in a buffer solution.
Synonymous with kinetic equivalence.