[ponyoponyo]

I need to know if my answer to this question is correct

What would be the comp of the first liquid to occur if a gas mixture containing 50% B were cooled from 100^oC?



I know the top line is the vapor line, the composition of the vapor which shows how much enrichment in the lower boiling component occurs. And I know the bottom line is the liquid line, the boiling point of the mixture.  think the answer would be 28% B. To do this I started at 50% B at the top of the graph, went straight down to the liquid line, went left to the vapor line, and then straight down the the B % composition and got 28% B. Is my thinking correct?

[curiouscat]

Think you are wrong. It will be ~70%.

As a cross check, Is A more volatile or B here?  Is the more volatile component concentrated in liq. or vap. phase?