Molecular Knowledge Systems,
Physical Property Estimation
There are numerous physical property estimation techniques which accurately predict a chemical's or mixture's physical properties. These techniques can be classified into two broad categories: group contribution techniques and equation oriented techniques. Group contribution estimation techniques begin with a compound's molecular structure. "Contributions" for each group found in the structure is totaled into an estimate. Once several basic properties are estimated by group contribution techniques these can be entered into equation oriented techniques for further property estimation.
Currently our web-based estimation requires you to manually enter the number of groups which occur within the structure being estimated. For example to estimate properties for butanol you would enter , 1 next to the -CH3 group, 3 next to the -CH2- group, and 1 next to the -OH group.
You can press the "Structures" choice box below for further examples of how to dissect molecular structures into groups.
Once you have entered the structure's groups scroll the window to examine estimated property values. For further information on group contributions and physical property estimation see the paper "Cranium: Component Software for Physical Property Estimation".
You may also want to download our Cranium Introduction Kit. This package contains Cranium, our physical property estimation program. Cranium goes far beyond this online estimation demonstration allowing you to draw molecular structures using the mouse, enter your own estimation techniques, and create and save your own databases.
|Molecular Weight||Joback Method|
|Melting Point||Joback Method|
|Boiling Point||Joback Method|
|Critical Temperature||Joback Method|
|Critical Pressure||Lydersen Method|
|Critical Volume||Joback Method|
|Enthalpy Formation, 298K||Joback Method|
|Gibbs Energy Formation, 298K||Joback Method|
|Enthalpy Fusion at Tm||Joback Method|
|Enthalpy Vaporization at Tb||Joback Method|
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