The chemical and other thermal constants of sodium and potassium

Abstract
The vapour-pressure equationdlnp/dt=λT/ RT2Can be intergrated when the variation with temperature ofλ, the latent heat of vaporisation, is known: this variation is given byλ0=λT+ ∫Tm0CspdT +fm+ ∫TTmC1pdT ― ∫T0CgpdT, whereλ0is the latent heat of vaporisation at absolute zero,fmthe latent heat of fusion, and the remaining Cpterms refer to the atomic heats at constant pressure of the solid, liquid and vapour. In the case of most metals there is considerable uncertainty as to the specific heat of the liquid and particularly in the cases of sodium and potassium. In this circumstance it is considered better to extrapolate the vapour-pressure equation to the melting point and to compute the integration constant C at that temperature from the equation log10p= ―λ0/4.575Tm+ Cgp/R log10Tm― ∫Tm0∫T0C3pdT/4.575T2·dT+C, wherepis the vapour pressure in atmospheres at the melting point Tm.

This publication has 29 references indexed in Scilit: