An amount of water of mass `m = 1.00 kg`, boiling at standard atmospheric pressure, turns completely into saturated vapour. Assuming the saturated vapour to be an ideal gas find the increment of entropy and internal of the system.

Explanation

From the first law of thermodynamics
`Delta U + A = Q = mq`
where `q` is the specific latent heat of vaporization
Now `A = p (V'_v - V'_l) m = m (RT)/(M)`
Thus `Delta U = m(q - (RT)/(M))`
For water this gives `~~ 2.08 xx 10^6`Joules.