Question

The vapour pressure of pure benzene at certain temperature is 0.85 bar. A non-
volatile, non-electrolyte solid weighing 0.5g when added to 39g of benzene (molar
mass 789), vapour pressure of the solution, then is 0.845 bar. What is the molar mass
of the solid substance?
(J - 2014 & 17)
5.89 of a non-volatile solute​

Answer 1

Answer:

789

Explanation:

789

Answer 2

Answer:

p^0-p^0/p^0 = W2 M1/W1 M2

P^0 = 0.850 bar = vapour pressure of pure benzene

P = 0.845 bar = vapour pressure of solution

W1 = 39g = mass of benzene

W2 = 78g = mass of solute

M1 = 78g/mol = Molar mass of benzene

M2 = Molar mass of solute

0.850 bar - 0.845 bar/0.850 bar = 0.5g×78g/mol/39g×M2

M2 = 170g/mol.