Thermodynamic properties of clathrates: II. The heat capacity and entropy of methane in the methane quinol clathrates

Measurements have been made of the heat capacity C p from ∼13 to ∼ 298°K of three clathrates of methane and β-quinol, in which 75·5, 45·7 and 16·5 per cent of the cavities were occupied by methane. Over the entire temperature range C p is found to be a linear function of composition. The contribution made to the heat capacity by a mole of methane has been analysed with the aid of the theory of J. H. van der Waals, and the rotational contribution found to be 3/2R, within experimental error, from about 150°k upwards, showing that rotation of the methane molecules is almost unrestricted. The heats of formation of several methane clathrates have also been measured calorimetrically.