Abstract
Calorimetric measurements have been carried out on a natural sample of mordenite from Goble, Oregon, having the composition Ca0.289Na0.361Al0.940Si5.060O12·3.468H2O 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:
| . | . | . | S°(T) − S°(0) [J/(mol·K)] . | . |
|---|---|---|---|---|
| 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. |
| . | . | . | S°(T) − S°(0) [J/(mol·K)] . | . |
|---|---|---|---|---|
| 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.
