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Unformatted text preview: cept of ideal solution and Raoult’s law are very useful, as even in the case, where the solution is not ideal, it will “to some extent” behave as an ideal solution, when the mixture is overwhelmingly rich in one of the components. For example, if we consider a solution of A and B, A will obey Raoult’s law, when xA becomes very close to 1 (solution = very dilute Marand’s Notes: Chapter 5  The Properties of Simple Mixtures 170 solution of B in almost pure A). Similarly, B will obey Raoult’s law, when the mole fraction of B is very close to 1 (solution = very dilute solution of A in almost pure B). You can see the analogy between the concepts real gas vs. ideal gas and real solution vs. ideal solution. In the case of gases, we said a real gas behaves ideally in the limit of low pressure, P. Here, we say Raoult’s law is obeyed for a given component of a mixture, when the mole fraction of that component approaches unity. Note that, when the mole fraction of a component (say A) approaches unity, this component follows Raoult’s law. However, such a solution does not rigorously behave ideally, because, the other component is very dilute in the mixture (xB is close to 0 if xA is close to unity) and therefore cannot obey Raoult’s law. However, from experiments carried out on binary mixtures (i.e. mixtures of two components A and B), we can see that when component A is almost pure (i.e. xA close to unity), then component B is dilute (xB close to zero) and the partial pressure of B abov...
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 Spring '07
 AREsker
 Physical chemistry, pH

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