Question

The water pressure of pure benzene at a certain temperature is 0.850 bar. A non-volatle , non-electrolyte
solid weighing 0.5g when added to 39.0 g of benzene (molar mass 78g mol-¹ ). Vapour pressure of the solution, then, 0.845 bar. What is the molar mass of the solid substance ?​

Answer 1

Answer:

ANSWER

p0p0−p=W1M2W2M1

p0=0.850bar= vapour pressure of pure benzene.

p=0.845bar= 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.

0.850bar0.850bar−0.845bar=39g×M20.5g×78g/mol

M2=170g/mol