This energy is positive and nearly

This energy is positive and nearly symmetrical about X2= 0.5 and depends on the enthalpy and entropy effects. Thus, if the mixture of alcohol with water is prepared, some hydrogen bonds are end other mically broken and the new ones are made exothermically and the enthalpy will be equal to the difference between these two thermal effects. Simultaneously, the loss of entropy takes place. From the thermodynamic properties of the water-ethanol mixture,it results that the entropy effect is a key factor for the changes of the excess of Gibbs free energy of ethanol and water mixing. Thus,a proper order of the associated alcohol and water molecules at X2= 0.5 has a higher contribution to the Gibbs free energy excess than disruption and formation of the hydrogen bonds in comparison to the “pure” water and alcohol. Probably, for these reasons aminimal excess of the sum of water and alcohol molar volumes isobserved at X2= 0.5.