Apparent Equilibrium Constants and Standard Transformed Gibbs Energies of Biochemical Reactions Involving Carbon Dioxide

1997 ◽  
Vol 348 (1) ◽  
pp. 116-124 ◽  
Author(s):  
Robert A. Alberty
Keyword(s):  
Carbon Dioxide ◽  
Equilibrium Constants ◽  
Biochemical Reactions ◽  
Gibbs Energies ◽  
Apparent Equilibrium

Some phase relationships between basic bismuth chlorides in aqueous solutions at 25 °C

1987 ◽  
Vol 65 (12) ◽  
pp. 2824-2829 ◽  
Author(s):  
Peter Taylor ◽  
Vincent J. Lopata
Keyword(s):  
Aqueous Solutions ◽  
Equilibrium Constants ◽  
Natural Occurrence ◽  
Chloride Solutions ◽  
Gibbs Energies ◽  
Activity Ratios ◽  
Aqueous Chloride ◽  
The Stability ◽  
Experimental Values ◽  
Phase Relationships

Observations are reported on the interconversion of solid α-Bi2O3, Bi12O17Cl2, BiOCl, and a daubréeite-like phase tentatively identified as Bi2O2(OH)Cl, in aqueous chloride solutions at 25 °C. Equilibrium constants, K, for these interconversions are expressed as anion activity ratios, {Cl−}/{OH−}. Experimental values of K for equilibrium between Bi2O3 and each of the chlorides are 100.56 ± 0.20 for Bi12O17Cl2, 101.5 ± 0.4 for Bi2O2(OH)Cl, and 103.13 ± 0.04 for BiOCl; the fatter two represent metastable equilibria. These equilibrium constants yielded the following estimates of Gibbs energies of formation: Bi12O17Cl2, −3141 ± 6 kJ mol−1;"Bi2O2(OH)Cl", −696 ± 4 kJ mol−1; BiOCl, −321.5 ± 1.3 kJ mol−1. Phase relationships among these solids are discussed, with reference to natural occurrence, other bismuth oxychlorides, and the stability of other basic salts of bismuth.

Article

1999 ◽  
Vol 77 (5-6) ◽  
pp. 934-942
Author(s):  
J Peter Guthrie
Keyword(s):  
Carbon Dioxide ◽  
Free Energy ◽  
Equilibrium Constants ◽  
Marcus Theory ◽  
Energy Of Activation ◽  
Free Energies ◽  
Orbital Theory ◽  
Activation Free Energy ◽  
Free Energy Of Activation ◽  
Rms Error

Rate constants for hydration of carbon dioxide and ketene can be calculated by applying No Barrier Theory, which needs only equilibrium constants and distortion energies, the latter calculated using molecular orbital theory. The calculated free energies of activation are in satisfactory agreement with experiment: the rms error in free energy of activation is 2.38 kcal/mol. These compounds can also be described using Marcus Theory or Multidimensional Marcus Theory using the transferable intrinsic barrier appropriate to simple carbonyl compounds; in this case the rms error in free energy of activation is 2.19 kcal/mol. The two methods agree on preferred mechanistic path except for uncatalyzed hydration of ketene where Multidimensional Marcus Theory leads to a lower activation free energy for addition to the C=O, while No Barrier Theory leads to a lower free energy of activation for addition to the C=CH2. A rate constant for hydroxide ion catalyzed hydration of ketene can be calculated and is in accord with preliminary experimental results.Key words: ketene, carbon dioxide, hydration, Marcus Theory, No Barrier Theory.

scholarly journals Standard electrode potentials involving radicals in aqueous solution: inorganic radicals (IUPAC Technical Report)

2015 ◽  
Vol 87 (11-12) ◽  
pp. 1139-1150 ◽  
Author(s):  
David A. Armstrong ◽  
Robert E. Huie ◽  
Willem H. Koppenol ◽  
Sergei V. Lymar ◽  
Gábor Merényi ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Literature Review ◽  
Equilibrium Constants ◽  
Experimental Results ◽  
Gibbs Energies ◽  
Electrode Potentials ◽  
Technical Report ◽  
Standard Electrode Potentials ◽  
Best Estimates

AbstractRecommendations are made for standard potentials involving select inorganic radicals in aqueous solution at 25 °C. These recommendations are based on a critical and thorough literature review and also by performing derivations from various literature reports. The recommended data are summarized in tables of standard potentials, Gibbs energies of formation, radical pKa’s, and hemicolligation equilibrium constants. In all cases, current best estimates of the uncertainties are provided. An extensive set of Data Sheets is appended that provide original literature references, summarize the experimental results, and describe the decisions and procedures leading to each of the recommendations.

scholarly journals Adjustment of K' to varying pH and pMg for the creatine kinase, adenylate kinase and ATP hydrolysis equilibria permitting quantitative bioenergetic assessment.

1995 ◽  
Vol 198 (8) ◽  
pp. 1775-1782 ◽  
Author(s):  
E M Golding ◽  
W E Teague ◽  
G P Dobson
Keyword(s):  
Creatine Kinase ◽  
Gibbs Energy ◽  
Adenylate Kinase ◽  
Atp Hydrolysis ◽  
Equilibrium Constants ◽  
Binding Constants ◽  
Acid Dissociation ◽  
Free Magnesium ◽  
Apparent Equilibrium ◽  
Energy Of Formation

Physiologists and biochemists frequently ignore the importance of adjusting equilibrium constants to the ionic conditions of the cell prior to calculating a number of bioenergetic and kinetic parameters. The present study examines the effect of pH and free magnesium levels (free [Mg2+]) on the apparent equilibrium constants (K') of creatine kinase (ATP: creatine N-phosphotransferase; EC 2.7.3.2), adenylate kinase (ATP:AMP phosphotransferase; EC 2.7.4.3) and adenosinetriphosphatase (ATP phosphohydrolase; EC 3.6.1.3) reactions. We show how K' can be calculated using the equilibrium constant of a specified chemical reaction (Kref) and the appropriate acid-dissociation and Mg(2+)-binding constants at an ionic strength (I) of 0.25 mol l-1 and 38 degrees C. Substituting the experimentally determined intracellular pH and free [Mg2+] into the equation containing a known Kref and two variables, pH and free [Mg2+], enables K' to be calculated at the experimental ionic conditions. Knowledge of K' permits calculation of cytosolic phosphorylation ratio ([ATP]/[ADP][Pi]), cytosolic free [ADP], free [AMP], standard transformed Gibbs energy of formation (delta fG' degrees ATP) and the transformed Gibbs energy of the system (delta fG' ATP) for the biological system. Such information is vital for the quantification of organ and tissue bioenergetics under physiological and pathophysiological conditions.

scholarly journals Single-Route Linear Catalytic Mechanism: A New, Kinetico-Thermodynamic Form of the Complex Reaction Rate

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1748 ◽  
Author(s):  
Gregory S. Yablonsky ◽  
Denis Constales ◽  
Guy B. Marin
Keyword(s):  
Reaction Rate ◽  
Catalytic Mechanism ◽  
Equilibrium Constants ◽  
Complex Reaction ◽  
Thermodynamic Factor ◽  
Kinetic And Thermodynamic Parameters ◽  
Kinetic Factor ◽  
Buffer Substance ◽  
Apparent Equilibrium ◽  
Thermodynamic Factors

For a complex catalytic reaction with a single-route linear mechanism, a new, kinetico-thermodynamic form of the steady-state reaction rate is obtained, and we show how its symmetries in terms of the kinetic and thermodynamic parameters allow better discerning their influence on the result. Its reciprocal is equal to the sum of n terms (n is the number of complex reaction steps), each of which is the product of a kinetic factor multiplied by a thermodynamic factor. The kinetic factor is the reciprocal apparent kinetic coefficient of the i-th step. The thermodynamic factor is a function of the apparent equilibrium constants of the i-th equilibrium subsystem, which includes the (n−1) other steps. This kinetico-thermodynamic form separates the kinetic and thermodynamic factors. The result is extended to the case of a buffer substance. It is promising for distinguishing the influence of kinetic and thermodynamic factors in the complex reaction rate. The developed theory is illustrated by examples taken from heterogeneous catalysis.

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