Partial molar property

The molar property of a component changes from its pure state property, when it is solution. for example the molar volume of pure water is 18.079 cm3/mol and when one mole of water is added to large volume of ethanol, the volume changes by 14 cm3, i.e. partial molar volume of water at infinite dilution is 14 cm3. the difference occurs due to the interaction between the particles. when water is pure, its molecules are surrounded by same kind of molecules, but in a water ethanol solution, water molecule is surrounded by both water molecules and ethanol molecules. The interaction forces in solution are different, thereby molecules have different partial properties. The interaction depends on the quantity of like and dislike molecules. So, partial molar property is composition dependent.
the ideal solution is defined as which has same interaction as in pure component. Therefore the molecules which have similar molecular properties, form an ideal solution.