Thermodynamic studies of mordenite, dehydrated mordenite, and gibbsite

G. K. Johnson; I. R. Tasker; H. E. Flotow; P. A. G. O'Hare; W. S. Wise

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Other| February 01, 1992

Thermodynamic studies of mordenite, dehydrated mordenite, and gibbsite

G. K. Johnson;

G. K. Johnson

Argonne Natl. Lab., Chem. Technol. Div., Argonne, IL, United States

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I. R. Tasker;

I. R. Tasker

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H. E. Flotow;

H. E. Flotow

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P. A. G. O'Hare;

P. A. G. O'Hare

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W. S. Wise

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Author and Article Information

G. K. Johnson

Argonne Natl. Lab., Chem. Technol. Div., Argonne, IL, United States

I. R. Tasker

H. E. Flotow

P. A. G. O'Hare

W. S. Wise

Publisher: Mineralogical Society of America

First Online: 02 Mar 2017

Online ISSN: 1945-3027

Print ISSN: 0003-004X

American Mineralogist (1992) 77 (1-2): 85–93.

Abstract

Calorimetric measurements have been carried out on a natural sample of mordenite from Goble, Oregon, having the composition Ca_0.289Na_0.361Al_0.940Si_5.060O₁₂·3.468H₂O and also on this same material in the dehydrated form. Low-temperature adiabatic calorimetry, high-temperature drop calorimetry, and solution-reaction calorimetry have been used to derive the thermodynamic properties of mordenite from T → 0 to 500 K and of dehydrated mordenite from T → 0 to 900 K. The following values have been obtained at T = 298.15 K and P⁰ = 0.1013 MPa:

	${Δ H}_{f}^{0} (T) (kJ/mol)$	$C_{P}^{0} (T) [J (kJ/mol \cdot K)]$	S°(T) − S°(0) [J/(mol·K)]	${Δ G}_{f}^{0} (T) (kJ/mol)$
mordenite	−6756.2 ± 4.5	484.33 ± 0.97	486.54 ± 0.97	−6247.6 ± 4.5
dehydrated mordenite	−5661.8 ± 4.6	295.76 ± 0.59	299.10 ± 0.60	−5338.6 ± 4.6.

	${Δ H}_{f}^{0} (T) (kJ/mol)$	$C_{P}^{0} (T) [J (kJ/mol \cdot K)]$	S°(T) − S°(0) [J/(mol·K)]	${Δ G}_{f}^{0} (T) (kJ/mol)$
mordenite	−6756.2 ± 4.5	484.33 ± 0.97	486.54 ± 0.97	−6247.6 ± 4.5
dehydrated mordenite	−5661.8 ± 4.6	295.76 ± 0.59	299.10 ± 0.60	−5338.6 ± 4.6.

The average binding energy and entropy of zeolitic H₂O in mordenite are 29.7 ± 1.8 kJ/mol and 54.05 ± 0.33 J/(mol·K), respectively. The enthalpy of formation of gibbsite, Al(OH)₃, which is an important auxiliary value used to derive the enthalpies of formation of aluminosilicates, was determined to be −1294.9 ± 1.2 kJ/mol. Revised enthalpy of formation and Gibbs energy of formation values are tabulated for analcime, dehydrated analcime, natrolite, scolecite, mesolite, and heulandite.