Ideal Liquid Mixtures. Vapour Pressure and Raoults Law

We shall discuss first the concept of the ideal liquid mixture (section 32.2) [i.e. one whose vapour pressure characteristics are such that they follow Raoult s Law (see below)] and contrast this with a real liquid mixture [i.e. one where non-ideal behaviour is exhibited and for which Raoult s Law is no longer obeyed]. We can then compare this concept of an ideal and real liquid mixture with that of ideal and real gases (Frame 31) showing that the ideas are fairly similar in nature and that parallels can be drawn and applied to their distinction and also that their definitions refer to limiting laws which apply. 

Obviously the more B molecules that are added to the mixture, the smaller will be xA(= 1 — Xb) (see equation (32.1)). 

2 Ideal Liquid Mixtures. Raoult s Law. Ideal Liquid Mixture of Involatile B and Volatile A 

A molecules all exerting a contribution to the total vapour pressure. 

Involatile B molecules represented by O exerting no contribution to the vapour pressure diminish the total vapour pressure exerted by the mixture. 

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