Enthalpies of formation and heat capacity functions for maricite,NaFePO4(cr), and sodium iron(III) hydroxy phosphate,Na3Fe(PO4)2· (Na4 / 3H2 / 3O)(cr)
✍ Scribed by Peter R. Tremaine; Caibin Xiao
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 162 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0021-9614
No coin nor oath required. For personal study only.
✦ Synopsis
Maricite, NaFe(II)PO 4 , and sodium iron(III) hydroxy phosphate ("SIHP"), Na 3 Fe(III) (PO 4 ) 2 • (Na 4/3 H 2/3 O), are recently discovered compounds that play an important role in phosphate-based water treatments for high-pressure steam generators in the electric power industry. Heat capacities of maricite and SIHP have been determined as a function of temperature by differential scanning calorimetry, and enthalpies of solution have been measured at T = 298.15 K in an isothermal calorimeter. These results lead to the following expressions for the standard molar heat capacity and enthalpy of formation of maricite and SIHP:
NaFePO 4 , cr, 298.15 K) = -(1571.8 ± 3.0) kJ • mol -1 ; and f H o m {Na 3 Fe(PO 4 ) 2 • (Na 4/3 H 2/3 O), cr, 298.15 K} = -(3830.8 ± 7.0) kJ • mol -1 .