Vibrational analysis of acetate ion molecules and estimation of equilibrium constants for their hydrogen isotopic exchange reactions

1983 ◽  
Vol 87 (14) ◽  
pp. 2526-2535 ◽  
Author(s):  
Masato Kakihana ◽  
Masahiro Kotaka ◽  
Makoto Okamoto
Keyword(s):  
Isotopic Exchange ◽  
Equilibrium Constants ◽  
Vibrational Analysis ◽  
Exchange Reactions

Isotopic Exchange and Equilibrium Fractionation

1999 ◽  
Author(s):  
Robert E. Criss
Keyword(s):  
Equilibrium Constant ◽  
Molecular Species ◽  
Equilibrium Condition ◽  
Isotopic Exchange ◽  
Equilibrium Constants ◽  
Hydrogen Gas ◽  
Common Element ◽  
Exchange Reactions ◽  
The Common ◽  
Two Phases

Equilibrium isotopic fractionations are best understood in terms of reactions that involve the transfer of isotopes between two phases or molecular species that have a common element (M). These isotopic exchange reactions may be written in one of several standard forms, such as . . . aAM*b + cBMd = aAMb + cBM*d (2.1) . . . where AMb and BMd represent the chemical formulas of the phases or species, AM*b and BM*d represent the same phases or species in which the trace isotope has replaced some or all of the atoms of element M, and a, b, c, and d are stoichiometric coefficients. In the case where all of the molecules are homogeneous, that is, where AMb and BMd are composed solely of the common isotope of M, and where AM*b and BM*d are phases or species in which the trace isotope M* has replaced all atoms of element M, then the product a × b equals c × d and represents the total number of atoms exchanged in the reaction. The concept of the isotopic exchange reaction is best shown by an example. Consider the exchange of deuterium between water and hydrogen gas. This may be written as a reaction among isotopically homogeneous molecules; that is, . . . H2O + D2 = D2O + H2 (2.2a) . . . or, alternatively, as exchange between homogeneous and heterogeneous molecules: . . . H2O + HD = HDO + H2 (2.2b) . . . Much of the utility of isotopic exchange reactions is that they may be described by equilibrium constants, defined in the standard way as the quotient of the activities of the products and reactants. Thus, the equilibrium condition for equation 2.2b becomes . . . K = ([HDO][H2])/([H2O][HD]) (2.3) . . . where K is the equilibrium constant. In equation 2.3, K has a particularly high value of 3.7 at 25°C.

Statistical mechanics of deuterium exchange reactions : relationships between equilibrium constants and enthalpies of reaction

1982 ◽  
Vol 35 (2) ◽  
pp. 237 ◽  
Author(s):  
DV Fenby ◽  
GL Bertrand
Keyword(s):  
Statistical Mechanics ◽  
Equilibrium Constant ◽  
Isotopic Exchange ◽  
Equilibrium Constants ◽  
Mechanical Analysis ◽  
Deuterium Exchange ◽  
Exchange Reactions ◽  
Statistical Mechanical

Bertrand and Burchfield proposed that the equilibrium constants K and the (standard) enthalpies ΔH of isotopic exchange reactions are related by the equation K = Kstatexp(-ΔH/RT) in which Kstat is the statistical (random) equilibrium constant. The application of this equation to deuterium exchange reactions for which experimental K and ΔH values are available suggests that it is a good approximation at 298 K. In this paper we present a statistical mechanical analysis to account for the success of the equation and to point out its limitations.

scholarly journals Calculation of Equilibrium Constants for Isotopic Exchange Reactions

1947 ◽  
Vol 15 (5) ◽  
pp. 261-267 ◽  
Author(s):  
Jacob Bigeleisen ◽  
Maria Goeppert Mayer
Keyword(s):  
Isotopic Exchange ◽  
Equilibrium Constants ◽  
Exchange Reactions

scholarly journals Isotopic Partition Function Ratios Involving H2, H2O, H2S, H2Se, and NH3

1973 ◽  
Vol 28 (2) ◽  
pp. 129-136 ◽  
Author(s):  
J. Bron ◽  
Chen Fee Chang ◽  
M. Wolfsberg
Keyword(s):  
Partition Function ◽  
Least Squares ◽  
Gas Phase ◽  
Isotopic Exchange ◽  
Equilibrium Constants ◽  
Heavy Atom ◽  
Harmonic Approximation ◽  
Ideal Gas ◽  
Correction Factors ◽  
Exchange Reactions

Ideal gas phase isotopic partition function ratios involving both deuterium and tritium substitution for hydrogen and also heavy atom substitution in H2, H2O, H2S, H2Se, and NH3 have been calculated at a number of temperatures. The results have been least squares fitted to a five term series in powers of (300/T). Various correction factors to the harmonic approximation were considered in the calculation of the partition function ratios. It is demonstrated that the tabulated ratios can be used to calculate equilibrium constants for isotopic exchange reactions.

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