RT Journal Article
SR Electronic
T1 The Determination of Intrinsic Activation Energies of Specific Acid-Base Catalyzed Reactions
JF PDA Journal of Pharmaceutical Science and Technology
JO PDA J Pharm Sci Technol
FD Parenteral Drug Association (PDA)
SP 205
OP 209
VO 36
IS 5
A1 Connors, Kenneth A.
YR 1982
UL http://journal.pda.org/content/36/5/205.abstract
AB Reactions catalyzed by hydronium ion or hydroxide ion (specific acid or specific base catalyzed reactions), when studied at controlled pH, can be described experimentally by pseudo-first-order rate constants that include the catalyst concentration or activity. Activation energies determined from Arrhenius plots using these pseudo-first-order rate constants will, in general, include contributions other than the intrinsic activation energy of the chemical reaction of interest. These extraneous contributions may include terms describing the dependence of activity coefficients on temperature, the variation of molar concentration with temperature, the heat of ionization of water, and the heat of ionization of a buffer acid. Quantitative expressions are derived for these effects, and experimental approaches are described that allow the intrinsic activation energy to be obtained.