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Heat capacity from 12 to 305°K and entropy of talc and tremolite

January 1, 1963

The heat capacities of talc, Mg3Si4O10(OH)2, and tremolite, Ca2Mg6Si8O22(OH)2, have been measured between 12 and 305°K. Smoothed values of heat capacity, entropy, enthalpy, and free energy are tabulated. At 298.15° K. the values of the thermodynamic functions are: talc, Cp°= 76.89 ± 0.23 cal. deg.-1 mole-1, S° = 62.33 ± 0.19 cal. deg.-1 mole-1, H° - H0° = 11,206 ± 34 cal. mole-1; tremolite, Cp° = 156.7 ± 0.6 cal. deg.-1 mole-1, S° = 131.2 ± 0.5 cal. deg.-1 mole-1, H° - H0° = 23,335 ± 90 cal. mole-1. From the equilibrium data of Bowen and Tuttle and the entropy of talc, the heat of formation of talc from MgO, SiO2, and H2O (liq.) is calculated to be ΔH°f298 = -43.6 ± 1 kcal.

Publication Year 1963
Title Heat capacity from 12 to 305°K and entropy of talc and tremolite
DOI 10.1021/j100805a003
Authors R. A. Robie, J. W. Stout
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Physical Chemistry
Index ID 70010783
Record Source USGS Publications Warehouse