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Parachor is a scientific quantity defined according to the formula:

P = γ1/4 M / d

where γ1/4 is the fourth root of surface tension, M is the molar mass, and d is the density.

Parachor "has been used in solving various structural problems".[1]


  1. ^ O. Exner. "Conception and Significance of the Parachor." Nature, 1 December 1962, vol. 196, pages 890-1.

As a part of a broader scheme dealing with empirical equations in organic chemistry, the parachor was also revised. Parachor is defined1 in equation (1), where y is the surface tension, d denotes the density and M the molecular weight: This expression is considered to be an additive quantity, that is, can be approximately expressed as a sum of empirical increments Pi corresponding to the single atoms or groups in the molecule. As an additive quantity the parachor has been used in solving various structural problems.