CaCl2-H2O in the supercritical and two-phase ranges

Abstract

Critical temperatures (T c ) and densities (πc) for aqueous CaCl2 solutions were measured using two different optical techniques, Measurements ofT c were made using sealed silica capillaries containing 0,3, 0,5, 1,0, and 2,0 molal CaCl2(aq)) solutions. TheT c values from these measurements are 661, 666, 678, and 738 K, respectively. Critical temperatures were also determined from measured homogenization temperatures and the observed mode of homogenization (i.e.. to the liquid or vapor phase or by fading of the meniscus) in synthetic fluid inclusions. Critical temperatures determined by the second method for 1.0, 2.0, and 3.0 molal CaCl2(aq) solutions are 680, 739, and 838 K. respectively. TheT c for 4.0 molal CaCl2(aq) was found to be in excess of 933 K, The capillary-tube measurements yield approximate values of the critical density ϱc, but do not give the critical pressureP c Approximate values ofT c ,. are available, however, from other sources.