[xoggyux]

My lab manual (Organic chemistry I lab have this question:
First they ask me to refer to one image and give me intructions how to read the graph explainin that each square represents 5%
they make me note that as the x axis increases benzene goes from 100% to 0% at the same time toluene goes from 0% to 100%
then they ask me
a-) What is the % composition of the vapor in equilibrium with a boiling liquid that has a composition of 30% benzene and 70% toluene?

b-) If a sample of vapor is found to have a composition of equal parts benzene and toluene, what is the composition of the boiling liqiod that produced this vapor?

I thought that if benzene is 30% in the liquid the it must be 70% in the vapor (or isent?) if so why so many intruction how to read the graph?

[nj_bartel]

If 9 parts of substance A, which boils at 1000 oC, are mixed with one part of substance B, which boils at 40 oC, and the mixture is heated to 50 oC, would you expect that 9 parts of substance A would be in the vapor for every one part of substance B?