# Raoult's law

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**Raoult's law** states that the vapour pressure of an ideal solution of components is:

where is the molar fraction of component , and is the vapour pressure of pure . More generally, Raoult's law describes the partial pressure of component in the vapour coexisting with a liquid mixture as:

- .

This law is obeyed for all components of an ideal solution, and is also obeyed for the solvent of an ideal dilute solution. The solute's partial pressure of such solutions then obey Henry's law. Ideal dilute solutions describe the limiting behaviour of a mixture of infinite dilution. Therefore, all solutions in the limit of infinite dilution obey Raoult's law, i.e.:

- .