Q. pA and pB are the vapour pressures of pure liquid components A and B, respectively, of an ideal binary solution. If xA represents the mole fraction of component A, the total pressure of the solution will be
A) pB + xA(pA − pB)
B) pA + xA(pB − pA)
C) pA + xA(pA − pB)
D) pB + xA(pB − pA)
Explanation
[Solution from source] By Raoult's law, p = pA·xA + pB·xB with xB = 1 − xA, so p = pB + xA(pA − pB). The expression starting with pA would require the mole fraction of B to multiply (pB − pA). Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.