This energy is positive and nearly symmetrical about X2= 0.5 anddepends on the enthalpy and entropy effects. Thus, if the mix-ture of alcohol with water is prepared, some hydrogen bonds areendothermically broken and the new ones are made exothermi-cally and the enthalpy will be equal to the difference between thesetwo 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 ofthe excess of Gibbs free energy of ethanol and water mixing. Thus,a proper order of the associated alcohol and water molecules atX2= 0.5 has a higher contribution to the Gibbs free energy excessthan disruption and formation of the hydrogen bonds in compari-son 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