Question
pA and pB are the vapour pressure of pure liquid components, A and B, respectively of and ideal binary solution. If xA represents the mole fraction of component A, the total pressure of the solution will be
-
pA + xA(pB-pA)
-
pA + xA(pA-pB)
-
pB + xA(pB-pA)
-
pB + xA(pA-pB)
Solution
D.
pB + xA(pA-pB)
Total pressure,
pT =p'A +p'B
We know that,
p'A =pAxA
p'B = pBxB
substituting the values of p'A and p'B in eq. (i)
pT = pAxA +pBxB
[xA+xB =1
xA = 1-xB or xB = 1-xA]
=pAxA +pB (1-xA)
=pAxA +pB -pBxA)
pT = pB +xA (pA-pB)
