question_answer 29)

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

Answer:

1 molal solution implies one mole of the solute dissolved in 1000g (1kg) of solvent i.e., water. No. of moles of solute (n2) = 1 mol No. of moles of water (n1) Mole fraction of solute                     = 0.0177 Now   On solving, Ps = 12.08 kPa.