Question

The vapour pressure of pure benzene at a certain
temperature is 640 mm Hg. A non-volatile solute
weighing 2.175 g is added to 39.0 g of benzene. The
vapour pressure of solution is 600 mm Hg. What is
the molar mass of the solute ? ​

Answer 1

Answer:

69.6 g is the right answer

Explanation:

Refer attachment for explanation!!!

Answer 2

Explanation:

Here you have to use the formula of relative lowering of vapour pressure which is

{P°- Ps÷P°}=Xb;Xb=mole fraction of solute

P°=vapour pressure of pure solvent

Ps=vapour pressure of solution

P°-Ps÷P°=1÷16=Xb

1÷16=2.175/Mb÷39.08/78 +2.175/Mb=>

then Mb=69.45 is the answer.

• Hope it helps you.