The values of change in enthalpy of activation (IH*), change in free energy of activation (IG*) and change in
entropy of activation (IS*) were calculated using following relations and tabulated in Table 4.
[DELTA]S[double dagger] is the
entropy of activation (J[mol.sup.-1][K.sup.-1]).
The corrosion parameters such as activation energy ([E.sub.a]), enthalpy of activation ([DELTA]H*), and entropy of activation ([DELTA]S*) for mild steel in 1 mol [L.sup.-1] HCl solution in the absence and presence of GAI with different concentrations (10-60 ppm) at various immersion periods in the temperature range of 303-323 K were calculated and tabulated (Table 4).
where N is Avogadro's number, h is Planck's constant, [DELTA]S* is the entropy of activation, and [DELTA]H* is the enthalpy of activation.
The opening up of the enzyme structure is accompanied by an increase in the disorder, randomness or
entropy of activation. The values of thermodynamic parameters were calculated from Figure 3(d).
The results showed that the values of 6G increase with increase in temperature due to increase in salt-solvent interaction.The change in
entropy of activation 6S is given by 27].
The
entropy of activation values in the absence and presence of inhibitor are negative.
The reactions were also studied at four different temperatures: 40, 50, 60, and 70 [degrees]C and the observed values of pseudo first-order rate constant, [k.sub.obs], were used to calculate the activation parameters of the various sugars, including their
entropy of activation reported in Tables 3a and b.
Whereas the negative values for
entropy of activation indicate that the activation complex has a more ordered or more rigid structure than the reactants and the reaction is slower than the normal(17).
The
entropy of activation ((delta)S [?] ), enthalpy of activation ((delta)H [?] ) and free energy of activation ((delta)G [?] ) of the main exothermic decomposition reaction of ACOF corresponding to T = T po , E a = E k and A = A k are obtained by Eqs.