In contrast, it is seen that for distribution system (B) there is only a small enthalpy change ,

and in this case a high entropy contribution

. This means that the distribution is not predominantly controlled by molecular forces. The entropy change reflects the loss of randomness or freedom that a solute molecule possessed when transferring from one phase to the other. The more random and 'more free' the solute molecule is to move in a particular phase, the greater its entropy in that phase. In system (B) the large entropy change indicates that the solute molecules are more restricted or less random in the stationary phase than they were in the mobile phase. Because the standard entropy is negative, this loss of freedom is responsible for a reduced distribution of the solute in the stationary phase and, thus, diminished solute retention. Inasmuch as the change in entropy in system (B) is the major contribution to the change in free energy,

the distribution, in thermodynamic terms, is said to be "entropically driven".

Chiral separations, or separations dominated by size exclusion are examples of separations that may be entropically driven systems. However, chromatographic separations need not be exclusively "energetically driven" or "entropically driven"; in fact, very few are. In most cases retention has both "energetic" and "entropic" components that, by careful adjustment, can be made to achieve very difficult and subtle separations. For example, if, as a result of its unique configuration, one enantiomer can interact more closely with the surface, and in doing so come closer to an energetically interacting group, both the enthalpy and entropy of the distribution will be changed. As a consequence, the separation of one isomer from its corresponding enantiomer will be achieved by both enthalpic (energy) and entropic contributions to the standard energy of distribution. The enthalpic contribution would, however, be a direct result of the proximity of the interacting groups with one another and, thus, will also be controlled by the primary entropic difference between the two enantiomers.

In the majority of distribution systems met in gas chromatography, the slope of the Vant Hoff curves are positive and the intercept negative. The negative value of the intercept means that the standard entropy change of the solute has resulted from the production of a less random and more orderly system during the process of distribution. More important, this entropy change reduces the magnitude of the distribution coefficient. This means that the greater the forces between the solute and stationary phase molecules, the greater the energy (enthalpy) contribution, the larger the distribution coefficient and the greater the retention. In contrast, any reduction in the random nature of the molecules or an increased amount of order in the system reduces the distribution coefficient and attenuates the retention. Thus, in the majority of distribution systems met in gas chromatography, the enthalpy and entropy changes oppose one another in their effect on solute retention. In fact there is considerable parallelism shown between the standard entropy and standard enthalpy of a series of solutes for a given distribution system.