Question

1) At 60 ∘C, compound X has a vapor pressure of 96mmHg, benzene (C6H6) has a vapor pressure of 395 mmHg, and a 50:50 mixture by mass of benzene and X has a vapor pressure of 284 mmHg .

A. What is the molar mass of X?

Answer 1

Solution :-

Lets assume we have 100 g mixture

50 g benzene and 50 g unknown

now lets calculate the moles of the benzene

moles of benzene = 50 g / 78.1118 g per mol = 0.6401

mole fraction equals to 1

so lets assume mole fraction of benzene = 0.6401

then mole fraction of the x= 1-0.6401 = 0.3599

now lets calculate the molar mass of x

molar mass of x= mass / moles

                       = 138.9 g per mol

So the molar mass of the X= 138.9 g per mol