Molecular Knowledge Systems, Inc.
Designing Better Chemical Products
Online Property Estimation


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.

Structure Entry

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.

dissect.gif (2308 bytes)

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.


Sorry: Online property estimation requires a browser which supports java.
Constant Properties
Property Technique Estimate
Molecular Weight Joback Method Sorry: Online property estimation requires a browser which supports java.
Melting Point Joback Method Sorry: Online property estimation requires a browser which supports java.
Boiling Point Joback Method Sorry: Online property estimation requires a browser which supports java.
Critical Temperature Joback Method Sorry: Online property estimation requires a browser which supports java.
Critical Pressure Lydersen Method Sorry: Online property estimation requires a browser which supports java.
Critical Volume Joback Method Sorry: Online property estimation requires a browser which supports java.
Enthalpy Formation, 298K Joback Method Sorry: Online property estimation requires a browser which supports java.
Gibbs Energy Formation, 298K Joback Method Sorry: Online property estimation requires a browser which supports java.
Enthalpy Fusion at Tm Joback Method Sorry: Online property estimation requires a browser which supports java.
Enthalpy Vaporization at Tb Joback Method Sorry: Online property estimation requires a browser which supports java.

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Copyright 1998-1999 Molecular Knowledge Systems, Inc.
Last modified: April 11, 1999