THERMODYNAMIC PROPERTIES OF 1-TRIMETHYLSILYL-1-PROPYNE FROM T=8 K TO T=330 K

In an adiabatic vacuum calorimeter the temperature dependence of the s tandard molar heat capacity C-p,m(o) of 1-trimethylsilyl-1-propyne (to tal mole fraction of impurities x = 0.0315) has been studied at temper atures between 8 K and 330 K, to within 0.2 per cent. The temperature and enthalpy of melting of the compound have been measured. The experi mental data were used to calculate the thermodynamic characteristics o f melting of 1-trimethylsilyl-1-propyne of 100 per cent purity: T-fus( o) = 204.42 K, Delta(fus)H(m)(o)/R = 1318 +/- 6, Delta(fus)S(m)(o)/R = 6.45 +/- 0.03 (where R is the universal gas constant) and the thermod ynamic functions in the range 0 K to 330 K, for T = 298.15 K and p = 1 01.325 kPa, C-p,m(o)/R = 26.76, Delta(0)(T)H(m)(o)/R . K = 6023, Delta (0)(T)S(m)(o)/R = 37.04, and Phi(m)(o)/R = 16.84. The isochoric heat c apacity C-V,C-m and its components, lattice C-V,C-lat,C-m and atomic C -V,C-at,C-m have been estimated in the range T --> 0 to T-fus(o). The first (A) and the second (B) cryoscopic constants have been determined . (C) 1997 Academic Press Limited.