Enthalpy-entropy compensation. 1. Some fundamental statistical problems associated with the analysis of van't Hoff and Arrhenius data

Krug, R. R.; Hunter, William G.; Grieger, R. A.

doi:10.1021/j100562a006

Cited by 680 publications

(382 citation statements)

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“…According to Krug et al (1976), linear chemical compensation or compensation theory only exists if the isokinetic temperature (TB) is different from the mean harmonic temperature (Thm). An approximate confidence interval, (1-α) 100%, for the isokinetic temperature was obtained by the following equation:…”

Section: Methodsmentioning

confidence: 99%

THERMODYNAMIC PROPERTIES OF BARU FRUITS (Dipteryx alata Vogel)

et al. 2017

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ABSTRACT:The objective of this study was to determine and evaluate the thermodynamic properties for different equilibrium moisture contents in baru fruits (Dipteryx alata Vogel), using the direct static method to obtain the experimental data. The Modified Halsey model was used to determine the thermodynamic properties of baru fruits. Results concluded that thermodynamic properties are influenced by moisture content. The water vaporization latent heat increases with the decrease in equilibrium moisture content. The baru fruit desorption process is controlled by enthalpy. Gibbs free energy is positive for the temperatures studied with the increase over desorption, which describes a non-spontaneous process.

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Section: Methodsmentioning

confidence: 99%

THERMODYNAMIC PROPERTIES OF BARU FRUITS (Dipteryx alata Vogel)

et al. 2017

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“…T β values for the sorption processes different from the harmonic mean temperature (T hm = 312.7 K) validate the application of the compensation theory in the present study. On turn, the fact that T β was greater than T hm both for adsorption and desorption indicates that both processes are governed by enthalpy (Krug et al, 1976). Moreover, values of ΔG β < 0 indicate that both processes are spontaneous (Slavutsky & Bertuzzi, 2015) and suggest strong intermolecular or binding interactions between water molecules and the product (related to enthalpy), which promotes a greater reduction in configurational freedom of the water molecules and, hence, a greater order in the system (related to entropy) (Xiao & Tong, 2013).…”

Section: From the Linear Regression Of Equation 12mentioning

confidence: 99%

“…On order to ratify the compensation theory, Krug et al, (1976) recommend a statistical test that compares the value of T β with the value of the harmonic mean temperature (T hm ) obtained by the Equation 13.…”

Section: Enthalpy-entropy Compensation Theorymentioning

confidence: 99%

Thermodynamic properties of Buriti (Mauritia flexuosa) tree gum

Silva

Pena

2018

Food Sci. Technol

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Moisture adsorption and desorption isotherms from buriti tree gum (BG) were obtained at different temperatures (25 to 55 °C) in a water activity range of 0.1 to 0.9. The isotherms were classified as type OO. The hysteresis loop and moisture of the monolayer decreased as temperature increased and Halsey's equation proved able to predict with good precision the product's sorption isotherms in the conditions studied. BG's isosteric heats of moisture adsorption and desorption were close to the latent heat of vaporization of pure water for moisture levels above 30 g/100 g db and exponentially increased below that level. The enthalpy-entropy compensation theory and the isokinetic relationship were applied and indicated that BG's moisture adsorption and desorption processes are spontaneous. The integral sorption properties indicated that the increase in surface tension at BG's moisture sorption sites was more representative for the desorption process.Keywords: Mauritia flexuosa; isotherm; water sorption; enthalpy; entropy. Practical application:The thermodynamic properties of sorption processes of gum from buriti tree were determined. These parameters are important to establish drying and storage conditions for the product.

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“…A teoria da compensação isocinética só e válida para o processo de sorção desde que haja uma relação linear entre entalpia e entropia (MADAMBA et al, 1996;TELIS et al, 2004). Krug et al (1976) recomendaram um teste simples que compara a temperatura isocinética (T B ) com a temperatura média harmônica (T hm ) obtida pela Equação 8.…”

Section: Oswinunclassified

Isotermas de dessorção de pimentão verde e energia envolvida no processo

Alves

Fóz

Nicoleti

2015

Braz. J. Food Technol.

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Isotermas de dessorção de pimentão verde e energia envolvida no processo Desorption isotherms of green bell peppers and the energy involved in the process*Autor Correspondente | Corresponding Author Recebido: Out. 01, 2014 Aprovado: Maio 18, 2015 ResumoEste trabalho teve como objetivos a obtenção das isotermas de dessorção do pimentão verde e a avaliação das propriedades termodinâmicas de sorção do fruto. As isotermas foram obtidas em função da temperatura (30°C, 40°C, 50°C e 60°C) em umidades relativas entre 4,0-90,0%. Os dados experimentais foram ajustados aos modelos matemáticos GAB, BET, Halsey, Henderson e Oswin para se descrever seu comportamento. Os resultados demonstram que o modelo de GAB descreveu com maior precisão as isotermas de dessorção do pimentão verde entre as faixas de atividade de água (a w ) selecionadas, em uma temperatura fixa. O calor isostérico de sorção (q st ) pôde ser determinado a partir de dados de sorção de umidade utilizando-se a derivada da equação de Clasius-Clapeyron, obtendo-se então o calor envolvido no processo de dessorção de umidade do pimentão verde fresco. A teoria da compensação entalpia-entropia ou isocinética foi aplicada aos dados experimentais, sugerindo que o processo de dessorção é conduzido pela entalpia. Palavras-chave: Calor isostérico; Secagem; Modelo de GAB; Compensação Entálpica-Entrópica. SummaryThis study aimed to obtain the desorption isotherms of green bell peppers and evaluate the thermodynamic properties of the moisture sorption of the fruit. The isotherms were obtained as a function of temperature (30°C, 40°C, 50°C and 60 °C) between 4.0 and 90.0% of relative humidity. The experimental data were fitted to the GAB, BET, Halsey, Henderson and Oswin mathematical models to describe their behaviour. The results showed that the GAB model described the sorption isotherms of green bell peppers with greater accuracy in the range of water activities (aw) selected, at a fixed temperature. The isosteric sorption heat (qst) could be determined from the moisture sorption data using the derivative of the Clasius-Clapeyron equation, to obtain the heat involved in the desorption process of the moisture of fresh green bell peppers. The enthalpy-entropy compensation or isokinetic theory was applied to the experimental data and suggested that the desorption process was driven by enthalpy.

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Enthalpy-entropy compensation. 1. Some fundamental statistical problems associated with the analysis of van't Hoff and Arrhenius data

Cited by 680 publications

References 3 publications

THERMODYNAMIC PROPERTIES OF BARU FRUITS (Dipteryx alata Vogel)

THERMODYNAMIC PROPERTIES OF BARU FRUITS (Dipteryx alata Vogel)

Thermodynamic properties of Buriti (Mauritia flexuosa) tree gum

Isotermas de dessorção de pimentão verde e energia envolvida no processo

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