Explain different types of non-ideal solutions. What is the cause of positive and negative deviations ?

Explanation

Types of non-ideal solutions . Non ideal solutions are of two types
1. Non - ideal solutions showing positive deviation. The total vapour pressure for such a solutions is greater than that corresponding to an ideal solution of same composition. This happens when interaction forces between A and B molecules in solution is less than A . . . . A and B . . . . interactions and thus their escaping tendencies increases. The boiling point of such solutions are relatively lower. It leads to slight increase in volume and absorptions of heat i . e., `Delta V_("mixing") and Delta H_("mixing") ` are positive .
Examples . Acetone - ethanol, Cyclohexane - ethanol , Ethyl acetate - water , Carbon disulphide - acetone
2. Non ideal solutions showing negative deviation . The total vapour pressure for such a solution is lower than that corresponding to an ideal solution of the same composition. This happens when the interactions forces between A and B molecules in solutions is more then that A . . . . A and B . . . . . B interactions and thus their escaping tendencies decreases. The boiling points of such solutions are relatively higher .It leads to slight decrease in volume and evolutions of heat i.e., `Delta V _("mixing") and Delta H _("mixing") ` are negative
Examples. Acetone - chloroform , Phenol - aniline , sulphuric acid - water , Hydrogen chloride - water