Question

the vapour pressure of a pure liquid a is 70 torr at 27 degrre Celsius it forms an ideal solution with another liquid b the mole fraction of b is 0.2 and total pressure of solutin is 84 torr at 28 degree Celsius the vapour pressure of pure liquid b at 27 degree Celsius

Answer 1

Dear Student,

According to Raoult's law, PT=PA°XA+PB°XBXB=0.2 So, XA=1−0.2=0.8 Now, 84=PA°×0.8+140×0.2or PA° = 70 torr