Page 263 - Thermodynamics of Biochemical Reactions

Chemical Equilibrium in One Phase Systems 263

0.308576

This agrees with the preceding plot.

3.3 Calculate the standard Gibbs energy changes and equilibrium constants in terms of species for the following reactions at
298.15 K and ionic strengths of 0, 0.10, and 0.25 M. Summarize the calculations in two tables.
(a) NAD- + H~ (g) = NADH~- + H'
(b) NADP3- + H2 (g) = NADPH4- + H+
(c) NAD- + NADPH4-= NADH2- + NADP3-
(d) CH3 CH2 OH + NAD- = CH3 CHO + NADH2- + H+
(e) CH3 CHO + NAD- + H2O = CH, C02 + NADH2- + 2 H+
(f) C3 H7 NO2 + NAD- + H20 = C3 H3 0-+ NADH2- + NH4 + + H+
The last reaction involves L-alanine and pyruvate.

(BasicBiochemData2 has to be loaded)

Since these reactants are all single species, calcdGis in the preceding problem can be used to calculate the function
that gives the standard Gibbs energy of formation. The values at these three ionic strengths can be calculated using the
assignment operation (/.). We can add the values for the products and subtract the values for the reactants to obtain the
values of the standard Gibbs energy for the reaction. Finally, we can calculate the corresponding equilibrium constants and
put them in a table.

=
calcdGis [species-] : Module [ {dGzero, zi, isterm),
(*This program calculates the function of ionic strength (is) that gives the
standard Gibbs energy of formation of a species at298.15 K. The input is
a list for the species that gives the standard Gibbs energy of formation,
the standard enthalpy of formation,the electric charge, and the number of
hydrogen atoms in the species. Energies are expressed in kJ mol*-l.*)
dGzero = species[[l]];
zi = species [ [ 31 ] ;
/
isterm=2.91482* (ziA2)*(isA.5) (1+1.6*isA.5);
dGzero - isterm]
hydroionis=calcdGis[hydro~onspl/.is->{O,.l,.25l

(0, -0.612064, -0.8096721

{0, -0.612064, -0.809672)

The Flatten is needed to remove the outer curly brackets in the BasicBiochemData2.

nadpredis=calcdGisCFlatten[nadpredspll /.is->{O,.l,.25};