Vapour pressure — UPSC Physics Optional CSE 2013 Paper I

The vapour pressure, in mm of Hg, of a substance in solid state is given by the relation \ln p=23.03-\dfrac{3754}{T}, where T is in Kelvin. The vapour pressure, in mm of Hg, of the substance in liquid state is given by the relation \ln p=19.49-\dfrac{3063}{T}. Calculate

(i) the coordinates of the triple point, and

(ii) the latent heat of vaporisation at the triple point. Take Gas constant R=8.314\ \mathrm{J\,mol^{-1}\,K^{-1}}.