1) The vapour pressure of a substance at 50.0°C is 43.0 kPa and its enthalpy of vaporization is 42.2 kJ mol^–1. Estimate the temperature at which its vapour pressure is 96.0 kPa. 

2) The normal boiling point of heptane is 98.4°C. Estimate (a) its enthalpy of vaporization and (b) its vapour pressure at 37°C and 84°C.  

3) The molar volume of a certain solid is 122.0 cm³ mol^–1 at 1.00 atm and 483.15 K, its melting temperature. The molar volume of the liquid at this temperature and pressure is 142.6 cm³ mol^–1. At 1.29 MPa the melting temperature changes to 485.34 K. Calculate the enthalpy and entropy of fusion of the solid.