Compressions and Solid Phases of CO2, CS2, COS, O2, and CO

Abstract

Compressions and phase diagrams for solid CO2, CS2, COS, O2, and CO are presented for pressures up to 10 000 atmos at low temperatures. A new modification of COS was observed under pressure.

The molar volume (density) of solid oxygen in equilibrium with vapor

“…A value of 1.19 cms/mol is obtained from the measurements of Barrett et a1. The value published by Stevenson [49] is 0..759 emS! mol.…”

“…The volume change for the /3-' Y transition has been measured directly at elevated pressures by Stevenson [49] and Stewart [50]. A value of 1.19 cms/mol is obtained from the measurements of Barrett et a1.…”

“…The heat of transition estimated from this paper is 10 J/mol, nearly a factor of ten smaller than the other values! The a-/3 transition has been measured at elevated pressure by both Stevenson [49] and Stewart [50]. Evidence that a volume change does indeed exist is found in figur.e 7 by Stevenson who calculates the volume change to be 0.117 CIIl 3 /11101 from the Clau~iu~ Clapeyron equation using the transition heat from Giauque and· Johnston [39]~ Stewart erroneously assumed the transition to be second order and did not present a volume change.…”

“…We adopt a value of 0.13 ± 0.11 cm 3 /mol for the volume change of the a-,8 transition as a composite of the results of the more recent experiments [10,41,49,50,55]. The uncertainty of the volume change is deliberately estimated as quite large because we feel .…”

“…The volume change can also be established from heats of fusion [39, 40, 41} and the pressure dependence of the 13-"( transition[49,50,81. The values 1,0 be consideI'ed aTe given in tabl~ 3.…”