Standard molar Gibbs free energy of formation of Pb5CrO8(s), Pb2CrO5(s), and PbCrO4(s)

Abstract

a b s t r a c tStandard molar Gibbs free energy of formation of ternary oxides Pb 5 CrO 8 (s), Pb 2 CrO 5 (s), and PbCrO 4 (s) were determined by measuring equilibrium oxygen partial pressures over relevant phase fields using manometry and solid oxide electrolyte based emf methods and are given by: D f G m Pb 5 CrO 8 ðsÞ AE 0:55=ðkJ Á mol À1 Þ ¼ À1809:4 þ 0:6845ðT=KÞ ð837 T=K 1008Þ; D f G m Pb 2 CrO 5 ðsÞ AE 0:30=ðkJ Á mol À1 Þ ¼ À1161:3 þ 0:4059ðT=KÞ ð859 T=K 1021Þ; D f G m PbCrO 4 ðsÞ AE 0:17=ðkJ Á mol À1 Þ ¼ À909:8 þ 0:3111ðT=KÞ ð863 T=K 1093Þ; Ó

Formation and Dehydration Enthalpy of Potassium Hexaniobate

“…Compounds with layered structures have interesting chemical properties applicable to fields such as photocatalysis, intercalation, ion exchange, photoluminescence, and electrochemistry . Semiconductor photocatalysts have attracted significant attention due to their potential industrial applications . Among various photocatalysts, TiO 2 has been widely researched due to its high activity, stability, and high photoinduction under ultraviolet (UV) light .…”

“…[1][2][3] Semiconductor photocatalysts have attracted significant attention due to their potential industrial applications. [4][5][6][7][8][9] Among various photocatalysts, TiO 2 has been widely researched due to its high activity, stability, and high photoinduction under ultraviolet (UV) light. 10 In recent years, a variety of metal oxides, including titanates, niobates, and tantalates with wide band gaps, have also been found to exhibit such properties.…”

The standard molar enthalpies of formation of Pb2CrO5(s) and Pb5CrO8(s) by acid solution calorimetry

“…Understanding the thermochemistry of ternary compounds of the (Pb + Cr + O) and (Pb + Fe + O) systems is of considerable interest in this regard. Preparation and thermal stability of the compounds existing in (Pb + Cr + O) system have been reported in the literature [2][3][4][5][6][7][8]. Three stable compounds, viz., PbCrO 4 (s), Pb 2 CrO 5 (s) and Pb 5 CrO 8 (s) exist in this system.…”

“…No corresponding data for Pb 2 CrO 5 (s) and Pb 5 CrO 8 (s) are available in the literature. Recently, the partial phase diagram of (Pb + Cr + O) system was established at the author's laboratory by long term equilibration studies [7] and also the standard molar Gibbs free energy of formation of Pb 5 CrO 8 (s), Pb 2 CrO 5 (s), and PbCrO 4 (s) were determined [8] by measuring equilibrium oxygen pressures over appropriate ternary phase fields either by manometry or by solid oxide electrolyte based emf cells. In the present work, the enthalpies of formation of Pb 2 CrO 5 (s) and Pb 5 CrO 8 (s) at T = 298 K have been determined using acid solution calorimetry.…”

Thermodynamics of Fe3O4–Co3O4and Fe3O4–Mn3O4spinel solid solutions at the bulk and nanoscale

“…As the applications of these spinels depend on their temperature range of stability and thermodynamic properties, numerous thermodynamic studies have been carried out on them, mostly at macroscopic level, with emphasis on free energies of formation and mixing [7][8][9][10][11][12][13][14][15][16][17][18][19][20] O 4 ) have been studied extensively, mainly by phase equilibrium and modeling methods 11,21,22 . The activity -composition relations in ternary solid solutions have been determined using electrochemical measurements and attempts were made to obtain enthalpies and entropies of mixing from the temperature dependence of EMF and other studies 23,24 Despite these earlier studies, separating the effects of enthalpy and entropy on the Gibbs energy of mixing in these complex solid solutions is difficult without independent calorimetric measurements of the enthalpy of mixing, which has only been done for the bulk Mn 3 Previous investigations suggest a number of spinel phases have lower surface energy than other oxides of the same metal 32 and it seems probable that this behavior can be extended to the transition metal spinel solid solutions.…”