Date of Award
Master of Science
Geological and Environmental Sciences
Dr. John D. Grace
Dr. Robert Hunt Anderson
Masters Thesis-Open Access
Stilbite is a calcium-rich zeolite found in low-grade metamorphic and hydrothermally altered environments. In this study, measurements of the enthalpy of formation at 298.15 K, heat capacity from 5 to 350 K, and enthalpy increments horn 350 to 500 K were performed on a specimen of stilbite characterized by electron microprobe analysis. The actual formula of the stilbite is: Ca1.019Na0.136K0.006Al2.180Si6.820O16 . 7.33H2O. Evaluation of the thermodynamic properties for stilbite at T = 298.15 K produced the following values: ΔrHOm(T)= -11034.6+6.6 kJ . mol-1, COp,m(T)=808.73+1.62 J.K-1, SOm(T)-SOm(0)=805.54+1.61 J.K-1.mol-1,ΔfSom(T)= -2990.44+1.86 J.K-1, mol-1, and ΔfGom(T)= -10143.0+6.6 kJ.mol-1. Comparison of the calorimetrically derived value for the Gibbs free energy of formation, ΔfGom, of stilbite with that calculated from an estimation method (La Iglesia and Anzar, 1986) shows a difference of 49 kJ.mol-1. An attem pt was made to retrieve a consistent Gibbs free energy value for laumontite using available phase equilbria and calorimetric data for heulandite and stilbite.
Howell, David Adams, "A Thermodynamic Study of the Zeolite Stilbite" (1987). Masters Theses. 1263.