6.2 (a) The molar volume of a certain solid is 161.0 cm3 mol-1 at 1.00 atm and 350.75 K, its melting temperature. The molar volume of the liquid at this temperature and pressure is 163.3 cm3 mol-1. At 1.00 atm the melting temperature changes to 351.26 K. Calculate the enthalpy and entropy of fusion of the solid.

(b) The molar volume of a certain solid is 142.0 cm3 mol-1 at 1.00 atm and 427.15 K, its melting temperature. The molar volume of the liquid at this temperature and pressure is 152.6 cm3 mol-1. At 1.2 MPa the melting temperature changes to 429.26 K. Calculate the enthalpy and entropy of fusion of the solid.

6.10 (a) Calculate the melting point of ice under a pressure of 50 bar. Assume that the density of ice under these conditions is approximately 0.92 g cm-3 and that of liquid water is 1.00 g cm-3.

(b) Calculate the melting point of ice under a pressure of 10 MPa. Assume that the density of ice under these conditions is approximately 0.915 g cm-3 and that of liquid water is 0.998 g cm-3.

Problem

6.2 Prior to the discovery that freon-12 (CF2Cl2) was harmful to the Earth’s ozone layer, it was frequently used as the dispersing agent in spray cans for hair spray, etc. Its enthalpy of vaporization

at its nomal boiling point of is 20.25 kJ mol-1. Estimate the pressure that a can of hair spray

using freon-12 had to withstand at , the the temperature of a can that has been standing in

sunlight. Assume that ∆vapH is a constant over the temperature range involved and equal to its value

at .