[Sis290025]

In diistillation, would the vapor above a solution of two volatile components contain both components but have more of the higher volatile component?

Thank you.

[mike]

You are partly right. You may want to read about Raoult's Law. The partial vapour pressure of a component in a mixture is equal to the vapour pressure of the pure liquid multiplied by the mole fraction of that component in the mixture.

This only really holds true for components in a mixture which are quite similar to each other, for example a mixture of hexane and heptane. However if it were a mixture of hexane and ether (which are different to each other) for example there is a deviation from this rule.

So back to your question, if the two components were in equal mole fractions (50/50) then the more volatile one would presumably have a higher vapour pressure and therefore a higher partial vapour pressure. If they had the same (or almost the same) vapour pressure then the component which was present in the higher amount would dominate.