What is meant by positive and negative deviation from Raoult's law and how is the sign of Delta H_(" mix") related to positive and negative deviations from Raoult's law ?

What is meant by positive and negative deviation from Raoult's law and

1.	What is meant by positive and negative deviation from Raoult's law and how is the sign of Delta H_(" mix") related to positive and negative deviations from Raoult's law ?
Answer» Solution :Positive deviations from Raoult.s law : Here the partial pressure component .A. in the mixture of .A. and .B. is more than that calculated from Raoult.s law. SIMILARLY, the partial vapour pressure of component .B. can be higher than calculated from Raoult.s law. For example, water and ethanol, chloroform and water, benzene and methanol, ACETIC acid and toluence, acetone and ethanol, methanol and `H_2O `. In other words, force of attraction between`A harr B lt A harr A and B harr B.` For positive deviation, `Delta H_("Mixing") = + ve and Delta V _("(mix)")= + v E` Negative deviations from Raoult.s law : (Here the partial vapour pressure of component .A. is FOUND to be less than calculated from Raoult.s law on adding the second component .B.. When .A. is added to .B., the partial vapour pressure of solution is less than that of ideal solution of same COMPOSITION. For example, chloroform and acetone, chloroform and methyl acetate, `H_2Oand HCI, H_2 O and HNO_3` etc.