Enthalpy and entropy of dissolution were studied.
The van’t Hoff equation relates the logarithm of mole fraction of a solute in an ideal solution as a linear function of the reciprocal of the absolute temperature as follows
where ΔdisH and ΔdisS are the enthalpy and the entropy of dissolution,
and C is the gas constant.
From the experimentally obtained solubility data,
plot of ln x1 versus 1/T gives the values of enthalpy and entropy of dissolution from the slope and the intercept, respectively.
Fig. 6 shows the van’t Hoff plot of the logarithm of mole fraction solubility versus reciprocal absolute temperature.
Table 3 lists the dissolution enthalpy and entropy.
From Table 3, it can be seen that the dissolution enthalpy of l-Gn in water is less than that in mixed solvents.