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{{Short description|Thermodynamic model}}
The '''Joback method''', often named '''Joback–Reid method''', [[Prediction|predicts]] eleven important and commonly used pure component thermodynamic properties from molecular structure only. It is named after Kevin G. Joback in 1984<ref>{{cite thesis|last=Joback |first=K. G.|date=1984 |title=A Unified Approach to Physical Property Estimation Using Multivariate Statistical Techniques |url=https://dspace.mit.edu/bitstream/handle/1721.1/15374/12352302-MIT.pdf?sequence=2 |type=MS |publisher=Massachusetts Institute of Technology}}</ref> and developed it further with Robert C. Reid.<ref>Joback K. G., Reid R. C., "Estimation of Pure-Component Properties from Group-Contributions", ''Chem. Eng. Commun.'', 57, 233–243, 1987.</ref> The Joback method is an extension of the [[Lydersen method]]<ref>Lydersen A. L., "Estimation of Critical Properties of Organic Compounds", University of Wisconsin College Engineering, ''Eng. Exp. Stn. Rep.'' 3, Madison, Wisconsin, 1955.</ref> and uses very similar groups, formulas, and parameters for the three properties the Lydersen already supported ([[critical temperature]], [[critical pressure]], critical volume).
Joback and Reid extended the range of supported properties, created new parameters and modified slightly the formulas of the old Lydersen method.
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=== Group-contribution method ===
[[Image:Gruppenbeitragsmethodenprinzip.
The Joback method is a [[group-contribution method]]. These kinds of methods use basic structural information of a chemical molecule, like a list of simple functional groups, add parameters to these functional groups, and calculate thermophysical and transport properties as a function of the sum of group parameters.
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<math>C_P[\text{J}/(\text{mol}\cdot\text{K})] = \sum a_i - 37.93 + \left[ \sum b_i + 0.210 \right] T + \left[ \sum c_i - 3.91 \cdot 10^{-4} \right] T^2 + \left[\sum d_i + 2.06 \cdot 10^{-7}\right] T^3.</math>
The Joback method uses a four-parameter polynomial to describe the temperature dependency of the ideal-gas heat capacity. These parameters are valid from 273 K to about 1000 K.
===Heat of vaporization at normal boiling point===
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