The vapour pressure of water is 12.3 kPa at 300 K. Calculate vapour pr

1.	The vapour pressure of water is 12.3 kPa at 300 K. Calculate vapour pressureof 1 molal solution of a non-volatile solute in it
Answer» Answer: The vapour pressure of water is 12.3 kPa at 300 K. We need to CALCULATE the vapour pressure of 1 molal solution of a non-volatile solute in it. 1000 g of water contains 1 MOLE of solute. The MOLAR mass of water is 18 g/mol. Number of moles of water = 18 1000 =55.56 mol Mole fraction of the solute in the solution is x= 1+55.56 1 =0.0177. The RELATIVE lowering in the vapour pressure is equal to the mole fraction of solute. p 0 p 0 −p =x 12.3 12.3−p =0.0177 ⇒p=12.08 Hence, the vapour pressure of the solution is 12.08 kPa.

The vapour pressure of water is 12.3 kPa at 300 K. Calculate vapour pressureof 1 molal solution of a non-volatile solute in it

Answer»

Answer:

The vapour pressure of water is 12.3 kPa at 300 K. We need to CALCULATE the vapour pressure of 1 molal solution of a non-volatile solute in it.

1000 g of water contains 1 MOLE of solute.

The MOLAR mass of water is 18 g/mol.

Number of moles of water =

1000

=55.56 mol

Mole fraction of the solute in the solution is x=

1+55.56

=0.0177.

The RELATIVE lowering in the vapour pressure is equal to the mole fraction of solute.

−p

12.3

12.3−p

=0.0177

⇒p=12.08

Hence, the vapour pressure of the solution is 12.08 kPa.