A solution has C6H6 and C7H8, and it is 25% C6H6 by mass. The vapour pressures are (at 298K): 94.2 torr for C6H6, and 28.4torr for C7H8.

Assuming ideal behaviour, calculate the following:
a) P of each sol'n comp's in mixture
b) P[tot] above sol'n
c) COMPOSITION OF VAPOUR IN MASS PERCENT***

Question

A solution has C6H6 and C7H8, and it is 25% C6H6 by mass. The vapour pressures are (at 298K): 94.2 torr for C6H6, and 28.4torr for C7H8.

Assuming ideal behaviour, calculate the following:
a) P of each sol'n comp's in mixture
b) P[tot] above sol'n
c) COMPOSITION OF VAPOUR IN MASS PERCENT***

anonymous · Answer

WAIT! I am going to photocopy my attempt.

anonymous · Answer

http://i1084.photobucket.com/albums/j409/QRAWarrior/CHMA11-HW-1.png

anonymous · Answer

attachment

mos1635 · Answer

a and b looks OK
let me see about c...

mos1635 · Answer

to find percent of each in vapours 
P1*V=n1*R*T=>...m1=P1*V*Mr1/R*T
P2*V=n2*R*T=>...m2=P2*V*Mr2/R*T
so (m1/m1+m2)*100%=.......
and (m2/m1+m2)*100%

anonymous · Answer

How did you get that?

anonymous · Answer

But I do not know volume...

anonymous · Answer

Should I assume that it is constant?

mos1635 · Answer

no it is same for both vapurs and goes away after substitution...

mos1635 · Answer

How did you get that? 
=equation of ideal gas

mos1635 · Answer

then set n=m/Mr and solve to m