- Heat and Molecular Physics 65
2.1 kJ/(kg •1(), the latent heat of fusion ofice is X = 340 kJ/kg, and the density of -ice
isP ice = 0•9p, (where pw is the density
of water).
Determine the mass Am of ice which melts
in the process and the work A done by an
external force if it is known that the pres-
sure required to decrease the fusion tempera-
ture of ice by 1 °C is p = 14 x 10^6 Pa,
while the pressure required to reduce the
volume of a certain mass of water by 1%
is p ' ----- 20 x 10^6 Pa.
(1) Solve the problem, assuming that wa-
ter and ice are incompressible.
(2) Estimate the correction for the com-
pressibility, assuming that the compres-
sibility of ice is equal to half that value
for water.
2.31. It is well known that if an ordinary
water is salted, its boiling point rises.
Determine the change in the density of
saturated water vapour at the boiling
point.
2.32. For many substances, there exists a
temperature Tu. and a pressure ptr at which
all the three phases of a substance (gaseous,
liquid, and solid) are in equilibrium. These
temperature and pressure are known as the
triple point. For example, Tt, = 0.0075 °C
and ptr = 4.58 mmHg for water. The la-
tent heat of vaporization of water at the
triple point is q = 2.48 x 10 3 kJ/kg, and
the latent heat of fusion of ice is X = 0.34 X
103 kJ/kg.
Find the latent heat v of sublimation0-0771