Standard transformed entropy

Note that although AfH ° values for species are independent of pH, this is not true for Af/T ° values of reactants consisting of two or more species because the r are functions of pH. The pseudoisomer group has a corresponding standard transformed entropy of formation given by... 

Enthalpies of Reaction from the Standard Enthalpies of Formation of Species II 10.3 Calculation of Standard Transformed Entropies of Biochemical Reactions I, 10.4 Effect of Temperature... 

CALCULATION OF STANDARD TRANSFORMED ENTROPIES OF BIOCHEMICAL REACTIONS... 

The determination of standard transformed enthalpies of biochemical reactions at specified pH, either from temperature coefficients of apparent equilibrium constants or by calorimetric measurements, makes it possible to calculate the corresponding standard transformed entropy of reaction using... 

Calculation of Standard Transformed Entropies of Biochemical Reactions... 

P number of different kinds of phases in a system Af standard transformed entropy of formation of... 

The corresponding standard transformed entropies of reaction are given by... 

R. A. Alberty, Standard molar entropies, standard entropies of formation, and standard transformed entropies of formation in the thermodynamics of enzyme-catalyzed reactions, J. Chem. Thermodyn., in press. 

The function of pH and ionic strength that yields the standard transformed entropy of formation of a reactants is obtained by the following program ... 

Module[ do, dH), ( This program derives the function of pH and ionic strength (is) that gives the standard transformed entropy of formation of a reactant (sum of species) at 298.15 K. The entropy is given in J K -1 mol -1. ) dG =calcdGmat[speciesmat] dH = calcdHmat[speciesmat] ... 

Table 3.3 Standard transformed entropies of formation in J K moP of inorganic phosphate at 298.15 K.

This program can be used to calculate standard transformed Gibbs energies of reaction, standard transformed enthalpies of reaction, standard transformed entropies of reaction and the change in the binding of hydrogen ions in a reaction. 

Changes of Standard Transformed Enthalpy of Reaction and Standard Transformed Entropy of Reaction with pH... 

Table 4.3 Standard transformed entropies of formation of inorganic phosphate in J K" moP at three temperatures, five pHs, and three ionic strengths...

The rate of change of the standard transformed entropy of formation with pH can be calculated in two ways (1) directly and (2) from the rate of change of the temperature times the average number of hydrogen ions bound with temperature, as shown in equation 3.4-13. 

The same table of standard transformed entropy of formation of inorganic phosphate can be calculated from the average number of hydrogen ions bound using... 

The standard transformed entropies of formation of these reactants are now calculated at 273.15 K. 

These standard transformed entropies of formation determine the contributions these reactants make to the apparent equilibrium constant for an enzyme-catalyzed reaction, but the more fundamental property, the standard molar entropies of species, are discussed in Chapter 15. 

It is of interest to see the extents to which the standard transformed enthalpy and standard transformed entropy of reaction determine whether the reaction goes spontaneously to the right or the left under specified conditions. 

This program is applied to the 90 reactions for which Af H° are known for all species. The reactions have all been written in the direction in which they are spontaneous at 298.15 K, pH 7, and 0.25 M ionic strength. The standard transformed Gibbs energies of formation and standard transformed enthalpies of formation are in kJ moP and the standard transformed entropies of formation are in J K" moP . 

This program is used to derive the functions of pH and ionic strength that give the standard transformed entropies of formation of all the reactants in Table 15.2. In the next section these functions are used to calculate the standard transformed entropies of reaction for four enzyme-catalyzed reactions. 

The standard transformed entropy of reaction at a specified pH can be calculated in two ways ... 

Table 15.5 gives the changes in standard transformed entropies for four reactions. 

Since these values are all positive, the change in standard transformed entropy favors reaction. 

---