Geochemical applications of the simple salt approximation to the lattice energies of complex materials

Yoder, Claude H.

doi:10.2138/am.2005.1537

Cited by 64 publications

(47 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It was attributed to the formation of barytocalcite since there was no reactivity between alumina and sodium nitrate before 600°C. The calculation of the enthalpy of the reaction, based on the additivity rule [25], has confirmed the negative value of this parameter. Based on the Eq.…”

Section: From Carbonated Precursorsmentioning

confidence: 62%

Study of barytocalcite as a conditioning matrix for carbon 14: Comparison of several synthesis routes

Massoni

Chartier

Cozzika

2013

Journal of Nuclear Materials

View full text Add to dashboard Cite

Section: From Carbonated Precursorsmentioning

confidence: 62%

Study of barytocalcite as a conditioning matrix for carbon 14: Comparison of several synthesis routes

Massoni

Chartier

Cozzika

2013

Journal of Nuclear Materials

View full text Add to dashboard Cite

“…Cu 4 SO 4 (OH) 6 (s) + CuSO 4 (aq) + 4H 2 O(l); DG o = À16 kJ/mol (1) The free energy for this reaction was calculated using literature values (Wagman et al, 1982) for free energies of formation of the products in the state shown and an estimation of the free energy of f o r m a t i o n ( À3 4 4 8 k J / m o l ) o f s o l i d Cu 5 (SO 4 ) 2 (OH) 6 .4H 2 O was calculated using the simple salt approximation given by Yoder and Flora (2005). That is, it is assumed that the essential reaction in the decomposition of Cu 5 (SO 4 ) 2 (OH) 6 .4H 2 O to brochantite is its reaction with water.…”

Section: Resultsmentioning

confidence: 99%

The relative stabilities of the copper hydroxyl sulphates

et al. 2007

Self Cite

View full text Add to dashboard Cite

The literature contains considerable disagreements on the relative stabilities of the members of the copper hydroxyl sulphate family. Titration of copper sulphate with sodium hydroxide is claimed by some to produce only brochantite, while other reports indicate that antlerite and a dihydrate of antlerite are produced in the titration. Most stability field diagrams show that antlerite is the more stable stoichiomer at pH 4 and sulphate activity of 0.05À1. We have reexamined this stoichiometric family by titration of aqueous copper sulphate with sodium hydroxide and sodium carbonate, reverse titration of sodium hydroxide with copper sulphate and simultaneous addition of copper sulphate and sodium hydroxide at a variety of mole ratios, concentrations, temperatures and reaction times. We have also explored the reaction of copper hydroxide with copper sulphate and the reaction of weak bases, such as sodium acetate, sodium carbonate and urea, with copper sulphate. Our work indicates that: (1) antlerite is not formed in reactions of 0.05 to 1.2 M CuSO 4 with 0.05À1.0 M NaOH or Na 2 CO 3 at room temperature; (2) antlerite is formed in the addition of small concentrations of base (40.01 M) to 1 M CuSO 4 at 80ºC, but not at room temperature or with 0.01 M CuSO 4 at 80ºC; (3) the formation of Cu 5 (SO 4 ) 2 (OH) 6 .4H 2 O occurs at large Cu 2+ to base mole ratios; (4) the compound described in the literature as antlerite dihydrate is actually Cu 5 (SO 4 ) 2 (OH) 6 .4H 2 O; (5) at mole ratios of Cu 2+ to OH À ranging from 2:1 to 1:2 the predominant product is brochantite; and (6) brochantite and Cu 5 (SO 4 ) 2 (OH) 6 .4H 2 O are converted to antlerite in the presence of 1 M CuSO 4 (the latter requires temperatures of 80ºC or greater).The K sp (ion activity product) values of antlerite and brochantite were determined to be 2.53 (0.01)610 À48 and 1.01 (0.01)610 À69 , respectively, using atomic absorption spectroscopy and Visual MINTEQ after equilibration in solutions of varying ionic strength and pH for six days. These values are in good agreement with those from the literature. However, after 6 months, antlerite in contact with solution is partially converted to brochantite and hence is metastable with a relatively low conversion rate. The K sp value for antlerite must therefore be considered approximate. The relative stabilities of the copper hydroxyl sulphates are rationalized using appropriate equations and Gibbs energy calculations. A Gibbs free energy of formation for Cu 5 (SO 4 ) 2 (OH) 6 .4H 2 O of À3442 kJ/mol was obtained from the simple salt approximation. The very restricted conditions required for the formation of antlerite are rationalized with a stability field diagram at 80ºC.

show abstract

“…with Mg and Ca addition because energy gains from hydration enthalpy and entropy might only have a minor influence (Cox and Parker 1973; Burgess 1978; Wulfsberg 1991). The lattice energy of these complex compounds can be calculated from the lattice energies of the individual salts using the “simple salt approximation” (Yoder and Flora 2005; Yoder and Rowand 2006). The lattice energies of α‐Fe 2 O 3 , MgO, and CaO, are 14309, 3795, and 3414 kJ/mol (Lide 2008), respectively, and suggest that the overall lattice energy may decrease if the amount of Mg and Ca in the Fe 2 O 3 ‐based compound increases.…”

Section: Discussionmentioning

confidence: 99%

Incorporation of Mg and Ca into Nanostructured Fe₂O₃ Improves Fe Solubility in Dilute Acid and Sensory Characteristics in Foods

Hilty

Knijnenburg²,

Teleki³

et al. 2010

Journal of Food Science

View full text Add to dashboard Cite

Iron deficiency is one of the most common micronutrient deficiencies worldwide. Food fortification can be an effective and sustainable strategy to reduce Fe deficiency but selection of iron fortificants remains a challenge. Water-soluble compounds, for example, FeSO(4), usually demonstrate high bioavailability but they often cause unacceptable sensory changes in foods. On the other hand, poorly acid-soluble Fe compounds, for example FePO(4), may cause fewer adverse sensory changes in foods but are usually not well bioavailable since they need to be dissolved in the stomach prior to absorption. The solubility and the bioavailability of poorly acid-soluble Fe compounds can be improved by decreasing their primary particle size and thereby increasing their specific surface area. Here, Fe oxide-based nanostructured compounds with added Mg or Ca were produced by scalable flame aerosol technology. The compounds were characterized by nitrogen adsorption, X-ray diffraction, transmission electron microscopy, and Fe solubility in dilute acid. Sensory properties of the Fe-based compounds were tested in 2 highly reactive, polyphenol-rich food matrices: chocolate milk and fruit yoghurt. The Fe solubility of nanostructured Fe(2)O(3) doped with Mg or Ca was higher than that of pure Fe(2)O(3). Since good solubility in dilute acid was obtained despite the inhomogeneity of the powders, inexpensive precursors, for example Fe- and Ca-nitrates, can be used for their manufacture. Adding Mg or Ca lightened powder color, while sensory changes when added to foods were less pronounced than for FeSO(4). The combination of high Fe solubility and low reactivity in foods makes these flame-made nanostructured compounds promising for food fortification. Practical Application: The nanostructured iron-containing compounds presented here may prove useful for iron fortification of certain foods; they are highly soluble in dilute acid and likely to be well absorbed in the gut but cause less severe color changes than FeSO(4) when added to difficult-to-fortify foods.

show abstract

Geochemical applications of the simple salt approximation to the lattice energies of complex materials

Cited by 64 publications

References 15 publications

Study of barytocalcite as a conditioning matrix for carbon 14: Comparison of several synthesis routes

Study of barytocalcite as a conditioning matrix for carbon 14: Comparison of several synthesis routes

The relative stabilities of the copper hydroxyl sulphates

Incorporation of Mg and Ca into Nanostructured Fe₂O₃ Improves Fe Solubility in Dilute Acid and Sensory Characteristics in Foods

Contact Info

Product

Resources

About

Geochemical applications of the simple salt approximation to the lattice energies of complex materials

Cited by 64 publications

References 15 publications

Study of barytocalcite as a conditioning matrix for carbon 14: Comparison of several synthesis routes

Study of barytocalcite as a conditioning matrix for carbon 14: Comparison of several synthesis routes

The relative stabilities of the copper hydroxyl sulphates

Incorporation of Mg and Ca into Nanostructured Fe2O3 Improves Fe Solubility in Dilute Acid and Sensory Characteristics in Foods

Contact Info

Product

Resources

About

Incorporation of Mg and Ca into Nanostructured Fe₂O₃ Improves Fe Solubility in Dilute Acid and Sensory Characteristics in Foods