Standard enthalpy of formation of disodium hydrogen phosphate hexahydrate and sodium diphosphate

Khaled, H. Gmati-Ben; Khattech, Ismail; Jemal, M.

doi:10.1016/j.jct.2010.11.008

Cited by 14 publications

(7 citation statements)

References 18 publications

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“…Considering this value with that obtained previously with Li and Na diphosphates [13,14], the drawing of the standard molar enthalpy of formation of the diphosphates as a function of that of the oxides (Fig. 4) shows a straight line with R 2 = 0.9739, suggesting a high correlation between these quantities and allowing to estimate the standard molar enthalpy of formation of potassium diphosphate as -3,187.8 kJ mol -1 .…”

Section: Discussionsupporting

confidence: 75%

“…This value needs to be checked by more recent experimental techniques. This work is the continuation of previous ones [13,14] and deals with a new determination of the standard molar enthalpy of formation of rubidium diphosphate through various processes of dissolution and mixing in aqueous phosphoric acid solutions [15] 'NH 4 H 2 PO 4 ' of a purity higher than 99 % (Fluka), were ground, in the appropriate proportion, in an agate mortar. The mixture was heated in a furnace using a platinum crucible.…”

Section: Introductionmentioning

confidence: 92%

“…Rb 4 P 2 O 7 can be involved in an hypothetical reaction including NaNO 3 (s), RbNO 3 (s), and Na 4 P 2 O 7 (s). The standard molar enthalpy of formation of the latter one has been determined in a previous work [13], those of NaNO 3 (s) and RbNO 3 (s) were picked from literature [20]. The following cycle, as shown in Fig.…”

Section: Cyclementioning

confidence: 99%

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Standard molar enthalpy of formation of rubidium diphosphate

Khaled

Khattech

Jemal

2014

J Therm Anal Calorim

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Rubidium carbonate (Rb 2 CO 3 ) and ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) were used for synthesizing rubidium diphosphate (Rb 4 P 2 O 7 ). The purity of the latter compound was checked up by X-ray diffraction. Rb 4 P 2 O 7 was involved in an hypothetical reaction and dissolved together with the other components in a 3.85 % (m/m) phosphoric acid solution, using a C-80 SETARAM calorimeter. Mixing processes were also realized in the calorimeter in order to get the standard molar enthalpy of formation of rubidium diphosphate (Rb 4 P 2 O 7 ). For that a thermochemical cycle was investigated and the obtained value for the standard molar enthalpy of formation of rubidium diphosphate is (-3,183.7) kJ mol -1 . The result is about 1.8 % lower than literature value.

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Section: Discussionsupporting

confidence: 75%

Section: Introductionmentioning

confidence: 92%

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Standard molar enthalpy of formation of rubidium diphosphate

Khaled

Khattech

Jemal

2014

J Therm Anal Calorim

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“…The diffractogram (Fig. 2) is in good agreement with the Findit database [34]. This latter shows that the final product is the sodium trimetaphosphate.…”

Section: Synthesis and Characterization Of Samplessupporting

confidence: 74%

Standard Formation Enthalpy of Na2O–ZnO–P2O5 Series Glasses

2018

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100 − x)NaPO 3 -xZnO (0 ≤ x ≤ 33 mol%) phosphate glasses have been prepared using the conventional melt quenching technique. Amorphous state was checked up by X-ray diffraction. Glasses have been investigated in detail by mean of differential scanning calorimetry, inductively coupled plasma. Incorporation of ZnO oxide increases the T g value and the thermal stability of samples. For this glass series, 31 P solid state magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy revealed the decrease of Q 2 tetrahedral sites and the increase of phosphate dimers (Q 1 ), when ZnO oxide is progressively introduced, suggesting the shortening of metaphosphate chains. Dissolution of glasses has been followed calorimetrically and showed a change in thermal signs resulting from the depolymerization of metaphosphate groups when ZnO oxide is added. A thermochemical cycle involving a number of dissolution and mixing processes have been carried out in order to get the standard enthalpy of formation of these glasses. Calculation of these quantities needs the standard enthalpy of formation of sodium trimetaphosphate. Formation enthalpy of glasses increases with the incorporation of ZnO oxide.

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“…In 1967, Irving et al [41] also utilized SCA to measure the enthalpy of formation of Na 3 PO 4 from its elements at 298 K. Subsequently, in 1968, Irving et al, [42,43] Krivtsov et al, [44] and Zhuang et al [45] determined the enthalpies of formation of Na 4 P 2 O 7 , Na 5 P 3 O 10 and NaPO 3 from their elements using the SCA method. In 2011, Khaled et al [46] measured the standard enthalpy of formation of Na 4 P 2 O 7 from its elements using the SCA method. These experimental results were incorporated into the present study with consideration for possible error margins.…”

Section: Systemmentioning

confidence: 99%

Thermodynamic Assessment of the P2O5-Na2O and P2O5-MgO Systems

Ye,

Li,

Yang

et al. 2024

Materials

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Knowledge about the thermodynamic equilibria of the P2O5-Na2O and P2O5-MgO systems is very important for controlling the phosphorus content of steel materials in the process of steelmaking dephosphorization. The phase equilibrium and thermodynamic data of the P2O5-Na2O and P2O5-MgO systems were critically evaluated and re-assessed by the CALPHAD (CAlculation of PHAse Diagram) approach. The liquid phase was described by the ionic two-sublattice model for the first time with the formulas (Na+1)P(O−2, PO3−1, PO4−3, PO5/2)Q and (Mg+2)P(O−2, PO3−1, PO4−3, PO5/2)Q, respectively, and the selection of the species constituting the liquid phase was based on the structure of the phosphate melts. A new and improved self-consistent set of thermodynamic parameters for the P2O5-Na2O and P2O5-MgO systems was finally obtained, and the calculated phase diagram and thermodynamic properties exhibited excellent agreement with the experimental data. The difference in the phase composition of invariant reactions from the experimentally determined values reported in the literature is less than 0.9 mol.%. The present thermodynamic modeling contributes to constructing a multicomponent oxide thermodynamic database in the process of steelmaking dephosphorization.

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Standard enthalpy of formation of disodium hydrogen phosphate hexahydrate and sodium diphosphate

Cited by 14 publications

References 18 publications

Standard molar enthalpy of formation of rubidium diphosphate

Standard molar enthalpy of formation of rubidium diphosphate

Standard Formation Enthalpy of Na2O–ZnO–P2O5 Series Glasses

Thermodynamic Assessment of the P2O5-Na2O and P2O5-MgO Systems

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