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The standard molar enthalpies of formation of PbBi12O19(s) and ϕ-Pb5Bi8O17(s) at 298.15 K were determined using an isoperibol calorimeter. The enthalpies of solution of ternary compounds, namely, PbBi12O19(s) and ϕ-Pb5Bi8O17(s) as well as stoichiometric oxide mixtures, namely, {PbO(s) + 6 Bi2O3(s)} and {5 PbO(s) + 4 Bi2O3(s)} in HNO3 (aq., 4.47 mol kg−1) at T = 298.15 K were measured. Using these values, Δ f H m o (298.15 K) of PbBi12O19(s) and ϕ-Pb5Bi8O17(s) were determined as (-3549.6 ± 23.8) kJ mol−1 and (-3239.4 ± 7.6) kJ mol−1, respectively. The given uncertainties were calculated as 2σ of the mean with 0.95 level of confidence.

The main aim of this work is to decrease the uncertainty of measuring of a laser beam power by isoperibol calorimeters. Measurement and calibration operating regimes of the isoperibol calorimeter are investigated experimentally. Temperature transients during the heating and cooling of the calorimeter core are studied. The differences of transient parameters in measurement and calibration operating regimes of the calorimeter are disclosed. Initial data for design of the calibration model of the isoperibol calorimeter are determined. It is recommended to take into account on a nonlinear thermalphysic characteristics of the core materials., Принципиально неустранимый вклад в бюджет неопределенности калибровки калориметрических первичных измерительных преобразователей (ПИП), входящих в состав государственных эталонов Украины, вносит неэквивалентность замещения лазерного излучения калибровочным тепловым потоком. Уменьшение неопределенности калибровки достигается выбором оптимальных параметров ПИП согласно его математической модели.В работе экспериментально определены исходные данные для построения адекватной модели ПИП с призматическим приемным элементом из графита. Приемный элемент ПИП поочередно облучался длинными импульсами лазерного излучения и калибровочного теплового потока и 2 раза в секунду регистрировалась его температура в течение процессов нагрева и остывания. Параметры переходных процессов вычислялись путем обработки накопленного массива данных. Алгоритм обработки позволил исключить сбои регистрирующей аппаратуры, выделить экспоненциальный участок переходного процесса и оценить влияние шумов.Получено, что калориметрический ПИП с графитовым призматическим приемным элементом удовлетворительно описывается линейной системой 1-ого порядка. Для дальнейшего уменьшения неопределенности ПИП с приемными элементами более сложной формы (коническая или бутылочная модели абсолютно черного тела) рекомендуется численно рассчитывать динамику температурного поля приемного элемента каким-либо вариантом метода конечных разностей.

The molar enthalpies of solution, ΔsolHm, for ionic liquid [C5mim][OAc] with different molalities were measured by the solution-reaction isoperibol calorimeter in the temperature range from 288.15 to 308.15 K with an interval of 5 K. According to Archer’s method, the standard molar enthalpies of solution, ΔsolHmθ, and the apparent relative molar enthalpy, ΦL, for [C5mim][OAc] were determined. In terms of Glasser’s theory of lattice energy, the hydration enthalpy of the cation, ΔH+ ([C5mim]+) = −178 kJ·mol–1 was obtained at 298.15 K. Compared with hydration enthalpy of [C2mim]+, ΔH+ ([C2mim]+) = −233 kJ·mol–1, the hydration of [C5mim]+ is weaker than [C2mim]+. The plot of ΔsolHmθ vs (T – 298.15) K is a good straight line and its slope is the standard molar heat capacity of solution, ΔCp,mθ = 231 J·K–1·mol–1, so that the specific heat capacity of solution, ΔCpθ = 1.09 J·g–1·K–1, was obtained for IL [C5mim][OAc].

The enthalpies of solution of ethylacetate (EtOAc) in water, octane and 1-octanol (OctOH) were measured at 298, 308 and 318 K using a precise isoperibol calorimeter. The standard enthalpies and heat capacities of these non-electrolyte solution were computed and compared with the previously obtained ΔsolH∘ and \(\Delta C_{p}^{\circ}\) values in N,N-dimethylformamide (DMF). Partial molal heat capacities of EtOAc in water and in organic solvents were calculated and compared with the available literature values.

Flower-like ammonium cadmium phosphate monohydrate was synthesized by solid-state reaction at low temperature and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, and elemental analysis. The product NH4CdPO4·H2O was obtained with flower-like morphology by the addition of fatty alcohol-polyoxyethylene ether surface-active agent. Based on Hess’s law, thermochemical cycle was designed to determine the dissolution enthalpies of reactants and products using a solution-reaction isoperibol calorimeter at 298.15 K, and the molar reaction enthalpy was calculated on the basis of above dissolution enthalpies. With the aid of other auxiliary thermodynamic data, the standard molar formation enthalpy of the title compounds was concluded: $$ \Updelta_{\text{f}} H_{\text{m}}^{-\!\!\!\!\circ} [{\text{NH}}_{4} {\text{CdPO}}_{4} \cdot {\text{H}}_{2} {\text{O}}] = ( - 1749.82 \pm 0.76)\; {\text{kJ}}\; {\text{mol}}^{ - 1} . $$

The standard molar reaction enthalpies of two reactions, CeCl3 · 7H2O(s) + 3CCl3COOH(s) = Ce(TCA)3· 3H2O(s) +3HCl(g) + 4H2O(1) (1) and Ce(TCA)3· 3H2O (s) + 2C9H7NO (S) = Ce(TCA) (C9H6NO)2 (s) + 2CCl3COOH(s) + 3H2O(1) (2), were investigated by classical solution calorimetry and an isoperibol calorimeter at 298.15 K. The standard molar enthalpies ΔsH·m of solution of CeCl3 · 7H2O(s), 3CCl3COOH(s), Ce(TCA)3 · 3H2O(s), Ce(TCA)3 · 3H2O(s), 2C9H7NO(s), Ce-(TCA) (C9H6NO)2(s) and 2CCl3COOH(s) were determined to be (50.615 ± 0.028), (23.431 ± 0.027), (94.206 ± 0.010), (54.151 ± 0.020), (27.485 ± 0.045), (106.392 ± 0.060) and-(14.893 ± 0.026) kJ/mol, respectively. The reaction enthalpies ΔrH⊖m of reactions (1) and (2) were obtained to be (204.279 ± 0.023) and-(9.863 ± 0.041) kJ/mol, respectively. According to the above results and the data given in literature, through Hess' law, the standard molar enthalpies ΔtH⊖m of formation of Ce(TCA)3 ± 3H2O(s) and Ce(TCA)(C9H6NO)2 (s) were estimated to be-(3060.0 ± 0.087) and-(1369.0 ± 0.292) kJ/mol, respectively.

The molar enthalpies of solution of VOSO4⋅3.52H2O(s) at various molalities in water and in aqueous sulfuric acid (0.1 mol⋅kg−1), ΔsolHm, were measured by a solution-reaction isoperibol calorimeter at 298.15±0.01 K. An improved Archer’s method to estimate the standard molar enthalpy of solution, \(\Delta_{\mathrm{sol}}H^{0}_{\mathrm{m}}\), was put forward. In terms of the improved method, the values of \(\Delta_{\mathrm{sol}}H^{0}_{\mathrm{m}}=-24.12\pm 0.03~\mbox{kJ}{\cdot}\mbox{mol}^{-1}\) of VOSO4⋅3.52H2O(s) in water and \(\Delta_{\mathrm{sol}}H^{0}_{\mathrm{m}}=-15.38\pm 0.06~\mbox{kJ}{\cdot}\mbox{mol}^{-1}\) in aqueous sulfuric acid were obtained, respectively. The data indicates that the energy state of VOSO4 in aqueous H2SO4 is higher than that in pure water.

The two complexes, [Ln(Ala)2(Im)(H2O)](ClO4)3 (Ln=Pr, Gd), were synthesized and characterized. Using a solution-reaction isoperibol calorimeter, standard enthalpies of reaction of two reactions: LnCl3⋅6H2O(s)+2Ala(s)+Im(s)+3NaClO4(s)=[Ln(Ala)2(Im)(H2O)](ClO4)3(s)+3NaCl(s)+5H2O(l) (Ln=Pr, Gd), at T=298.15 K, were determined to be (39.26±0.10) and (5.33±0.12) kJ mol–1 , respectively. Standard enthalpies of formation of the two complexes at T=298.15 K, ΔfHΘm {[Ln(Ala)2(Im)(H2O)](ClO4)3(s)} (Ln=Pr, Gd), were calculated as –(2424.2±3.3) and –(2443.4±3.3) kJ mol–1 , respectively.

Lanthanum tellurites, La2Te3O9 and La2Te4O11, have been prepared by the solid state synthesis route and characterized for their phase and chemical compositions by XRD and ICP-AES analyses. The molar enthalpies of solution of La2Te3O9(s), La2Te4O11(s), La2O3(s) and TeO2(s) in 0.150 dm3 of 10.98 mol dm−3 HCl were measured using an isoperibol calorimeter. From these results and other auxiliary data the standard molar enthalpy of formation of La2Te3O9(s) and La2Te4O11(s) were derived to be (−2814.6 ± 12.9) kJ mol−1 and (−3116.5 ± 17.3) kJ mol−1, respectively, at 298.15 K which are the first reported thermodynamic data on these compounds at 298.15 K.

The crystals of four complexes of rare earth perchlorate with dl -α-alanine and imidazole were synthesized and characterized. The components of them were determined to be [RE(C 3 H 7 NO 2 ) 2 (C 3 H 4 N 2 )(H 2 O)](ClO 4 ) 3 (RE: Sm, Eu, Dy, Er) by FT-IR, chemical, elemental and thermal analysis. The enthalpies of dissolution of [2C 3 H 7 NO 2 (s) + 3NaClO 4 (s)], [C 3 H 4 N 2 (s) + RECl 3 ·6H 2 O(s)] and [3NaCl(s)], {[RE(C 3 H 7 NO 2 ) 2 (C 3 H 4 N 2 )(H 2 O)](ClO 4 ) 3 (s)} were determined by a solution–reaction isoperibol calorimeter at T =298.15 K, respectively. According to Hess’s law, the standard molar enthalpies of reaction of four reactions, RECl 3 ·6H 2 O(s) + 2C 3 H 7 NO 2 (s) + C 3 H 4 N 2 (s) + 3NaCl(s) = [RE(C 3 H 7 NO 2 ) 2 (C 3 H 4 N 2 )(H 2 O)](ClO 4 ) 3 (s) + 3NaCl(s) + 5H 2 O(l) (RE: Sm, Eu, Dy, Er) were determined to be 4.87±0.20, 7.23±0.19, 0.96±0.27 and 12.88±0.32 kJ mol −1 , respectively. The standard molar enthalpies of formation of the four complexes at T =298.15 K, Δ f H m Θ {[Re(C 3 H 7 NO 2 ) 2 (C 3 H 4 N 2 )(H 2 O)](ClO 4 ) 3 (s)} (RE: Sm, Eu, Dy, Er), were determined to be −(2448.1±3.3), −(2360.3±3.3), −(2451.8±3.3) and −(2444.3±3.3) kJ mol −1 , respectively.

Using an on-line solution-reaction isoperibol calorimeter, the standard molar enthalpies of reaction for the general thermochemical reaction: LnCl3·6H2O(s) + 2C9H7NO(s) + CH3COONa(s) = Ln(C9H6NO)2(C2H3O2)(s) + NaCl(s) + 2HCl(g) + 6H2O(l) (Ln: Nd, Sm), were determined at T=298.15 K, as −(56.9±1.4) and −(67.9±1.5) kJ mol−l, respectively. From the mentioned standard molar enthalpies of reaction and other auxiliary thermodynamic quantities, the standard molar enthalpies of formation of Ln(C9H6NO)2(C2H3O2)(s) (Ln: Nd, Sm), at T=298.15 K, have been derived to be: −(1494.7±3.3) and −(1501.5±3.4) kJ mol−l, respectively.

Crystals of two coordination compounds of rare earth chlorides with glycine, [Ln(Gly)3(H2O)2]Cl3·2H2O (Ln = Pr, Nd; Gly = glycine), were prepared and characterized. Using a solution-reaction isoperibol calorimeter, the standard molar enthalpies of reaction for the general thermochemical reaction, LnCl3·6H2O(s) + 3Gly(s) = [Ln(Gly)3(H2O)2]Cl3·2H2O(cr) + 2H2O(l) (Ln = Pr, Nd; Gly = glycine), were determined at T = 298.15 K, as (19.2 ± 0.4) kJ·mol-l and (63.4 ± 0.5) kJ·mol-l, respectively. From the above standard molar enthalpies of reaction and other auxiliary thermodynamic quantities, the standard molar enthalpies of formation of [Ln(Gly)3(H2O)2]Cl3·2H2O (Ln = Pr, Nd; Gly = glycine), at T = 298.15 K, have been derived to be −(3875.7 ± 1.1) kJ·mol-l and −(3825.2 ± 1.1) kJ·mol-l, respectively.

The standard enthalpies of formation at 300 K of the RNiAl phases (R=rare earth) have been obtained by using a high temperature direct reaction drop calorimeter and an aneroid isoperibol calorimeter. State and composition of the samples were checked by X-ray diffraction analysis. Metallographic examination was performed and the phases were further identified by electron microscopy and electron probe microanalysis. The results obtained are discussed and compared with those available for the binary RNi 2 and RAl 2 compounds.

A simple isoperibol calorimeter, using the modified method of mixtures, was developed to measure the average specific heat capacity of different dough types between 20 and 90°C. The method consisted of encapsulating the sample in a copper cylinder and immersing the capsule in water at a different temperature. The procedure was tested for reliability with distilled water and whole fat milk before applying it to five dough types of varying moisture and fat contents. Mean values of 4.176±0.008 kJ kg-1 K-1 and 3.942±0.034 kJ kg-1 K-1 were obtained for distilled water and milk respectively, which agree within 0.23 and 0.34% from reported values. The specific heat values for the five dough types were found to range between 2.15–2.68 kJ kg-1 K-1 between 2.35–3.10 kJ kg-1 K-1 and between 2.40–3.19 kJ kg-1 K-1 at the three temperature levels studied. The specific heat capacity was found to depend not only on the moisture level but also on the fat content, especially for dough types with a high percent of fat. Regression analysis was then used to correlate these values and develop a set of empirical equations. The results were used to assist in energy balance calculations in backing oven for industrial purposes.

The enthalpies of dilution for aqueous solutions of [Co(en)3]Br3, [Co(pn)3]Cl3, and [Co(tn)3]Cl3 (where en = 1,2-diaminoethane, pn = 1,2-diaminopropane, and tn = 1,3-diaminopropane) have been measured at 25°C, and up to m = 1 mol-kg−1, using an isoperibol calorimeter by the “long-jump” method. Relative apparent molar enthalpies Lφ have been extracted as an empirical equation relating Lφ and m. Previously reported experimental data and theoretical predictions in the restricted primitive model (RPM) for 3:1 and 1:3 aqueous electrolytes are shown together with the new experimental material.

The following reactions 2 Zn ( Ac ) 2 ·2 H 2 O ( s )+ H 5 IO 6 ( s )→ Zn 2 HIO 6 ·1.25 H 2 O ( s )+4 HAc ( l )+2.75 H 2 O ( l ) 2 Cd ( Ac ) 2 ·2 H 2 O ( s )+ H 5 IO 6 ( s )→ Cd 2 HIO 6 ·1.25 H 2 O ( s )+4 HAc ( l )+1.25 H 2 O ( l ) 2 Cu ( Ac ) 2 · H 2 O ( s )+ H 5 IO 6 ( s )→ Cu 2 HIO 6 ·2 H 2 O ( s )+4 HAc ( l ) have been studied. The molar dissolution enthalpies of the reactants and products in a certain solvent (3 M l −1 HNO 3 ) of this three reaction have been measured using an isoperibol calorimeter at 298 K. From these values, combined with auxiliary values, the standard molar formation enthalpies of Zn 2 HIO 6 ·1.25H 2 O (s), (298.2 K), Cd 2 HIO 6 ·1.25 H 2 O (s), (298.2 K) and Cu 2 HIO 6 ·2H 2 O (s), (298.2 K) have been determined to be Δ f H m θ (Zn 2 HIO 6 ·1.25 H 2 O (s), 298.2 K) = −1342.11 kJ mol −1 , Δ f H m θ (Cd 2 HIO 6 ·1.25H 2 O (s), 298.2 K) = −1405.49 kJ mol −1 and Δ f H m θ (Cu 2 HIO 6 ·2H 2 O (s), 298.2 K) = −1226.08 kJ mol −1 .

In this paper we are setting the bases for the elaboration of energy maps of forest biomass. It shows the results obtained from the calculation of the calorific values and of the flammabilities of each of the forest species studied in Galicia (NW, Spain) along the year. With these data, it is possible to classify the species in terms of their energy content and of their resistance to forest fire. This classification is useful to draw realistic energy maps. With them, it will be possible to prevent and fight forest fires more effectively. These studies are complemented with chemical analyses of each forest species and bioclimatic diagrams of the areas to be studied. The main equipments used to carry out this research were an isoperibol calorimeter with agitated liquid in a static bomb, an epiradiator, an atomic absorption spectrophotometer and tools for elementary analyses.

The molar enthalpies of solution of SrTeO3, SrTe2O5, TeO2, and SrCO3in HCl (aq,c=11 mol·dm−3) have been measured by using an isoperibol calorimeter. From these results and other auxiliary data, the standard molar enthalpies of formation ΔfHm°(298.15 K) of SrTeO3(cr) and SrTe2O5(cr) have been calculated to be −(1026.0±10.7) kJ·mol−1and −(1381.2±12.9) kJ·mol−1, respectively. These values of enthalpies of formation are consistent with the second-law enthalpies of formation derived from their vapour pressures determined in this laboratory by a transpiration technique.

The solid-state coordination reaction: 2HSAO(s) + Ni(Ac) 2 (s) → Ni(SAO) 2 (s) + 2HAc(g) 2HSAO(s) + Co(Ac) 2 ·4H 2 O(s) → Co(SAO) 2 ·2H 2 O(s) + 2HAc(g) + 2H 2 O(g) have been studied by classical solution calorimetry. The molar dissolution enthalpies of the reactants and the products in a certain solvent (for one reaction is in 6 mol l −1 HCl and another in a mixed solution consisting of DMSO and DMF) of this two solid-solid coordination reactions have been measured using an isoperibol calorimeter. From the results and other auxiliary quantities, the standard molar formation enthalpies of [Co(SAO) 2 ·2H 2 O, s, 298.2 K] and [Ni(SAO) 2 , s, 298.2 K] at 298.2 K have been determined to be Δ f H θ m [Co(SAO) 2 ·2H 2 O, s, 298.2 K] = −957.205 kJ mol −1 and Δ f H θ m [Ni(SAO) 2 , s, 298.2 K] = −403.336 kJ mol −1 .

The molar enthalpies of solution of CaTeO3, CaTe2O5, TeO2, and CaCO3in HCl(aq,c=11 mol·dm−3) have been measured by using an isoperibol calorimeter. From these results and other auxillary data, the standard molar enthalpies of formation ΔfHm°(298.15 K) of CaTeO3(s) and CaTe2O5(s) have been calculated to be −(985.4±4.8) kJ·mol−1and −(1337.4±7.2) kJ·mol−1, respectively. These values are consistent with the second law enthalpies of formation of the compounds determined in this laboratory by a transpiration technique.

An isoperibol calorimeter is described. Its operation involves the drop of a sample from temperatures up to 1373 K into a metal block at 298.15 K. By this method the enthalpy contents of the samples can be measured. The calibration factor, obtained by electrical and drop calibrations, had a reproducibility of ±0.11%. The calorimeter was tested by determining the enthalpy of silver; agreement with the data of Barin was within a range of ±1%.

The molar enthalpies of solution of ZrTe 3 O 8 , TeO 2 , and ZrF 4 , in HF(aq) of concentration 10 mol.dm −3 have been measured using an isoperibol calorimeter. From the results and other auxiliary quantities, the standard molar enthalpy of formation of ZrTe 3 O 8 (s) has been determined to be Δ f H m °(298.15 K) = −(2119.2 ± 9.6)kJ·mol −1 .

Four compounds in the system Li 2 O-MoO 3 , namely, Li 2 MoO 4 (c), Li 2 Mo 2 O 7 (c), Li 2 Mo 3 O 10 (c) and Li 2 Mo 4 O 13 (c) were synthesized and characterized by both chemical and X-ray diffraction analyses and confirmed to be single-phase compounds. The molar enthalpies of solution of these compounds have been measured at 298.15 K using an isoperibol calorimeter and the respective values at infinite dilution, Δ sol H m α (298.15 K), for the compounds Li 2 MoO 4 (c), Li 2 Mo 2 O 7 (c), Li 2 Mo 3 O 10 (c) and Li 2 Mo 4 O 13 (c) are −(33.88 ± 0.51), −(97.68 ± 0.52), −(167.20 ± 0.30) and −(247.68 ± 0.88) kJ mol −1 respectively. These data were used to calculate the standard molar enthalpies of formation Δ f H m o (298.15 K) and the respective values for the compounds are −(1520.13 ± 0.94), −(2279.29 ± 1.76), −(3032.68 ± 2.53) and −(3775.26 ± 3.46) kJ mol −1 . The results are compared with the available data in the literature.

The molar enthalpies of solution of ThMo 2 O 8 , Mo, and ThF 4 in (10 mol dm −3 HF(aq) + 4.41 mol dm −3 H 2 O 2 (aq)) have been measured using an isoperibol calorimeter. From these results and other auxiliary data, the standard molar enthalpy of formation of ThMo 2 O 8 has been calculated to be Δ f H m 0 (298.15 K) = (−2742.2 ± 4.5) kJ mol −1 . This value of enthalpy of formation of ThMo 2 O 8 is consistent with the second law enthalpy of formation of ThMo 2 O 8 determined in this laboratory by transpiration technique.

The following reactions 2 Zn ( Ac ) 2 ·2 H 2 O ( s )+ H 5 IO 6 ( s )→ Zn 2 HIO 6 ·1.25 H 2 O ( s )+4 HAc ( l )+2.75 H 2 O ( l ) 2 Cd ( Ac ) 2 ·2 H 2 O ( s )+ H 5 IO 6 ( s )→ Cd 2 HIO 6 ·1.25 H 2 O ( s )+4 HAc ( l )+1.25 H 2 O ( l ) 2 Cu ( Ac ) 2 · H 2 O ( s )+ H 5 IO 6 ( s )→ Cu 2 HIO 6 ·2 H 2 O ( s )+4 HAc ( l ) have been studied. The molar dissolution enthalpies of the reactants and products in a certain solvent (3 M l −1 HNO 3 ) of this three reaction have been measured using an isoperibol calorimeter at 298 K. From these values, combined with auxiliary values, the standard molar formation enthalpies of Zn 2 HIO 6 ·1.25H 2 O (s), (298.2 K), Cd 2 HIO 6 ·1.25 H 2 O (s), (298.2 K) and Cu 2 HIO 6 ·2H 2 O (s), (298.2 K) have been determined to be Δ f H m θ (Zn 2 HIO 6 ·1.25 H 2 O (s), 298.2 K) = −1342.11 kJ mol −1 , Δ f H m θ (Cd 2 HIO 6 ·1.25H 2 O (s), 298.2 K) = −1405.49 kJ mol −1 and Δ f H m θ (Cu 2 HIO 6 ·2H 2 O (s), 298.2 K) = −1226.08 kJ mol −1 .

The important amount of hydration water in the ulexite (NaCaB5O9.8H2O), allows using calcination methods to increase its B2O3 content. This paper analyses the thermal decomposition reaction of a preconcentrated ulexite through weight loss measurements, which occur during the heating of samples until 1000 oC. Determinations of heat content at each temperature were made using an isoperibol calorimeter. The mean specific heat was calculated from these values, and its dependence on temperature was determined. The maximum weight loss was about 32.5 % and the specific heat obtained was 1,13 kJ/kgoC for solid samples and 1,38 kJ/kgoC for fluid samples.The results are useful for the design of the industrial process, in order to determine the thermal requirements for heating calcined ulexite, and to obtain smelted ulexite.

The enthalpies of dilution for aqueous solutions of [Co(en)3]Cl3, where en = 1,2-diaminoethane, have been measured at 25°C, and up to m = 1 mol-kg-1, using a new large isoperibol calorimeter by the >long-jump> method. Relative apparent molar enthalpies Lφ have been extracted as an empirical equation relating Lφ and m. Comparison with other 3:1 and 1:3 aqueous systems confirms the previously suggested hydrophobic character of the [Co(en)3]3+ cation.

Dr. Shyamala Bharadwaj is presently Head, Fuel Cell Materials & Catalysis Section, Chemistry Division, Bhabha Atomic Research Centre, Mumbai, India. She obtained her M.Sc. in Chemistry in 1981 and her Ph.D. in Physical Chemistry in 1991 from Mumbai University. Her main area of work during the past 30 years has been determination of thermodynamic properties of nuclear materials using various techniques such as vapour pressure measurements, thermogravimetry, isoperibol calorimeter, etc. During 2000–2001, she worked as guest scientist at Juelich Research Centre, Juelich, Germany on Solid Oxide Fuel Cell (SOFC) materials. Her current interests are in the fields of Intermediate Temperature Solid Oxide Fuel Cells (ITSOFC) and sulphur–iodine thermochemical cycle for generation of hydrogen from water. She was awarded the NETZSCH–ITAS Award (2006) by the Indian Thermal Analysis Society in the year 2006 for her contributions in the field of thermal analysis. She has more than 95 papers in refereed international journals and more than 100 papers in National and International Symposia. She served two terms (2003–2009) as Hon. General Secretary of Indian Thermal Analysis and during this period she was involved in organizing several national symposia and workshops on Thermal Analysis. She has been one of editors of Proceedings of National Symposium on Thermal Analysis held biennially at various places in India during the period 1991 to 2010.

Heat capacities of ethylamine + water + lithium bromide (H2O:LiBr = 2:1 mass) were measured using a twin isoperibol calorimeter devised for high-pressure measurements in the range of temperatures from 313.15 K to 373.15 K and in the range of ethylamine concentrations from 0 to 50.3 mass %. An empirical equation of the heat capacity for this ternary system was obtained as a function of temperature by a least-squares method from experimental data. Maximum and average absolute deviations between the experimental data measured and the calculated values from this empirical equation were 0.3% and 0.1%, respectively.

The enthalpies of solution of crystalline AlCl 3 and KBr were measured successively in one portion of 3.5 mol dm −3 HCl solution as well as AlBr 3 and KCl in another. The measurements were carried out in a 100 cm 3 reaction vessel of the isoperibol calorimeter LKB-8700. The standard enthalpy of the resulting reaction: A l C l 3 ( c ) + 3 K B r ( c ) = A l B r 3 ( c ) + 3 K C l ( c ) , was found to be Δ H r o ( 298.15 K ) = ( 6 3 . 4 ± 1 . 3 ) k J m o l - 1 which leads to Δ H f o ( A l B r 3 , c , 2 9 8 . 1 5 K ) = ( - 5 1 2 . 6 ± 1 . 9 ) k J m o l - 1 . The same measurements were carried out for AlCl 3 and KI and for AlI 3 and KCl. The standard enthalpy of the reaction: A l C l 3 ( c ) + 3 K I ( c ) = A l I 3 ( c ) + 3 K C l ( c ) , was found to be Δ H r o ( 298.15 K ) = ( 8 0 . 1 ± 1 . 4 ) k J m o l - 1 which leads to Δ H f o ( A l I 3 , c , 2 9 8 . 1 5 K ) = ( - 3 0 2 . 9 ± 2. 0 ) k J m o l - 1 .

The heats of formation in the Y- Pb system have been measured by using a differential direct isoperibol calorimeter. Compositions and the state of the samples were checked by chemical, metallographic and X-ray analyses. The following values (kcal/g-at.) were obtained for the various compounds (reaction in the solid state, ΔH300K): Y 5 Pb 3 : ΔH = −16.0 ± 0.5; Y 5 Pb 4 : ΔH = −14.4 ± 0.5 YPb 2 : ΔH = − 8.9 ± 0.5; YPb 3 : ΔH = − 6.7 ± 0.5 . These data have been compared with those obtained for the La-Pb and Y-Bi alloys and are discussed briefly in relation to the model suggested by Miedema (J. Less-Common Metals, 32 (1973) 117).

The enthalpies of the reactions of Zr(cr), ZrCl 1.09 (cr), and ZrCl 4 (cr) with (1.0HF + 2.9HCl) mol · dm −3 solution were measured in 0.1 dm 3 reaction vessel of the isoperibol calorimeter LKB-8700. The following standard molar enthalpies of formation were calculated: Δ f H m o (298.15 K)/(kJ · mol −1 ): ZrCl 1.09 (cr), −330.5 ± 2.4; ZrCl(cr), −303.2 ± 3.4; ZrCl 2 (cr), −531.0 ± 5.0; ZrCl 4 (cr), −980.7 ± 1.0. Heat-capacity measurements between 9 and 315 K were performed on pure samples of ZrCl 0.98 (cr) and ZrCl 4 (cr). The following standard molar thermodynamic quantities of crystal zirconium chlorides are reported at T ′ = 298.15 K: ZrCl ZrCl 2 ZrCl 4 C p, m o (T′)/( J · K −1 · mol −1 ) 47.26 ± 0.10 75 116.80 ± 0.20 S m o (T′)/( J · K −1 · mol −1 ) 60.94 ± 0.12 100 180.40 ± 0.35 “H m o (T′) − H m o (0)’/(J · mol −1 ) 9324 ± 10 14200 24590 ± 50 Δ f G m o (T′)/( kJ · mol −1 ) −276.5 ± 3.4 −482.7 ± 5.0 −889.9 ± 1.0

A precision isoperibol calorimeter with automatic data acquisition and processing, capable of operating over a wide temperature range, has been constructed and tested. The calorimeter was designed to have a very low thermal modulus and fast equilibration time. A small vapor space above the liquid and a vapor trap make the calorimeter useful for measurements with nonaqueous solvents. Time–temperature data are automatically recorded in digital form on magnetic tape and processed on a Univac 1106 computer. A series of electrical calibrations causing a temperature rise of 0.13 K were reproducible to about 0.01%. Several determinations of the enthalpy of reaction of a standard sample of Tris (hydroxymethyl) aminomethane with 0.1 N HCl gave an average value of 29.764±0.013 kJ/mol, which agrees satisfactorily with published results.

Heats of formation in the Dy-Bi system have been measured using a small furnace isoperibol calorimeter. The composition and states of the alloys were checked by chemical, metallographic and X-ray analyses. For the Dy-Bi compounds the following values were obtained for reaction in the solid state at 300 K: Dy 5+ x Bi 3 , ΔH = −19.5 ± 0.5 kcal (g atom) −1 ( x = 0); DyBi, ΔH = −23.0 ± 0.5 kcal (g atom) −1 . The results obtained are compared with those of other rare earth bismuthides and are discussed briefly.

The excess enthalpies were investigated for 12 binary and 4 ternary systems, including mixtures and solutions of electrolytes and non-electrolytes. The excess enthalpies of mixtures and integral heats of solutions were measured with an isoperibol calorimeter at 35 °C. Heats of fusion and heat capacities as functions of temperature were measured with a Perkin Elmer Corp., DSC-2. Integral heats, heats of fusion and heat capacities allow investigations of excess enthalpies of solutions. For modelling of the experimental results, the modified Redlich-Kister equation was used with good success.

Heats of formation in the Nd-Sb system were measured using a differential direct isoperibol calorimeter. The composition and state of the samples were checked by chemical, metallographic and X-ray analysis. The following values (±0.5 kcal (g atom)−1) of ΔHform were obtained for the various compounds (reaction in the solid state at 300 K): Nd5Sb3, −25.75; Nd4Sb3, −27.2; NdSb, −29.4; NdSb2, −21.7. These data have been compared with those previously obtained for the Nd-Bi systems and correlated, using the Miedema relationship, with the data for several bismuthides and antimonides.

A more exact method of calculating the heat loss from isoperibol-calorimeter reaction vessels is described. This method involves corrections for changes in the heat-leak constant and the external power input with changes in the calorimeter contents, and is particularly important for reaction vessels with volumes of less than 25 cm3 or with heat-leak constants greater than about 0.005 min−1. The new calculation has been tested by application to results collected with a titration calorimeter of capacity 3 cm3.

Literature values of the enthalpy of formation of perchlorate ion are based solely on measurements of the enthalpy of decomposition of crystalline perchlorates and are in poor agreement. In this paper a new method—measurements of the enthalpies of reaction in solution—was used. The enthalpies of reduction of crystalline KClO4 and KBrO3 by TiCl3 solution were measured in the 100 cm3 reaction vessel of LKB-8700 isoperibol calorimeter. The enthalpies of solution of crystalline KCl and KBr were measured similarly in the same solution. The values ΔHfo(KClO4, c, 298.15 K) = − (431.41 ± 0.87) kJ mol−1, and ΔHfo(ClO4−, aq, 298.15 K) = − (127.79 ± 0.86) kJ mol−1, were calculated from appropriate thermochemical cycles.

An aneroid isoperibol calorimetric apparatus is described which is particularly suitable for measurement of the reaction heat among solids. Such an apparatus contains four calorimeters and allows to carry out differential measurements. Each calorimeter includes two small electric furnaces employed for heating the solid mixture until the reaction begins and for the successive electric calibrations, respectively. The temperature trend of each calorimeter is followed by 80 thermocouples in series. The instrument characteristics are briefly discussed. Examples of its employment in the alloy thermochemistry are given.

The dynamic characteristics of an isoperibol solution calorimeter with electrical heating are discussed on a theoretical basis. The design requirements of a solution calorimeter are briefly reviewed. A calorimeter which satisfies these requirements was conducted and is described here. The dynamics of solutions heating by an electrical heater are mathematically developed and computer generated heating curves are compared to experimental curves.