Question

If water at 0°C, kept in a container with an open top, is placed in a large evacuated chamber,

(a) all the water will vaporize

(b) all the water will freeze

(c) part of the water will vaporize and the rest will freeze

(d) ice, water and water vapour will be formed and reach equilibrium at the triple point

Answer 1

Correct Answer is: (c)

Let Ls = specific latent heat of vaporization,

LI = specific latent heat of freezing.

Given, Ls = ηLI.

Let m = initial mass of water, f = fraction of water frozen.

Mass of vapour formed = m(1 - f), mass of ice formed = mf.

m(1 - f)Ls = mfLI

or 1 - f/f = LI/Ls = 1/η

or η - ηf = f

or f = η/η + 1 .