vapor pressure A = X
vapor pressure B = Y
total p of vapor = Ptotal = Xav + Ybv
Xa in vapor = Xav/(Xav + Ybv) = 0.3
Xb in vapor = Ybv/(Xav + Ybv) = 0.7
In liquid
Xa liq = Poa liq*0.3/Ptotal vapor = Poa liq/(Xav + Ybv)
Similarly for Xb liq =
Xb = Pob liq/(Xav + Ybv)
I hope this is not too confusing. Calling the vapor pressure of A and B X and Y along with mole fractions in both vapor and liquid can get very confusing. If you get confused let me suggest you do this.
Suppose we had Aliq = Po of 100 mm and we had Xa = 0.6 along with Bliq = Po of 200 mm and Xb = 0.4
We can calculate Pa and Pb this way.
Pa = Xa*Poa = 0.6*100 = 60 mm
Pb = Xb*Pob = 0.4*200 = 80 mm
Total vapor pressure above liquid is 60+80 = 140 mm.
Xa vapor = 60/140 = about 0.429
Xb vapor = 80/140 = about 0.571
Now watch. We want to take the Xa and Xb in the vapor and get the Xa and Xb in liquid (ans we know what those numbers are).
Xa liq = Xav*Ptotal/Po = 0.429*140/100 = 0.6
Xb liq = Xbv*Ptotal/Po = 0.571*140/200 = 0.4
Using these numbers may help in understanding the X and Y stuff above.
Xa liq =
and B = Po of 200
Liquid A has vapor pressure X, and liquid B has vapor pressure Y. What is the mole fraction of the liquid mixture if the vapor above the solution is 30% A by moles? 50% A? 80% A? (calculate in terms of x and y)
I'm a little bit confused because I thought the mole fraction of the vapor pressure and of the solution were the same. But I guess not? Thank you so much!
2 answers
Ignore the last two lines; i.e., Xa liq =
and B = Po of 200. Those were below my screen from earlier attempts and I didn't get them erased. The rest of it looks ok to me.
and B = Po of 200. Those were below my screen from earlier attempts and I didn't get them erased. The rest of it looks ok to me.