A. A. Abramzon and M. B. Petel’skii
St. Petersburg State Technical University, ul. Politekhnicheskaya 29, St. Petersburg, 195251 Russia
Received March 20, 1996
Abstract—The topical problem of predicting the transport properties of substances, such as viscosity and dif-
fusion, is considered. Coefficient n values, which show what amount of intermolecular bonds are broken in vis-
cous flow or diffusion, are analyzed. The dependence of the activation energy of transfer processes on the struc-
ture of molecules of a liquid is studied. It is shown that aliphatic n-hydrocarbons up to eicosane have activation
energies additive with respect to the number of carbon atoms in the aliphatic chain. At larger chain lengths, the
increment per carbon atom decreases, which implies chain coiling. Coefficient n is virtually constant over the
whole homologous series of hydrocarbons up to 40 carbon atoms in the chain, which means that chain confor-
mation variations have the same effect on the activation energy of viscous flow and the energy of vaporization.
The dependence of coefficient n on isomerization in the aliphatic chain is analyzed to show that increasing
branching causes n to decrease following a linear dependence. This dependence is shown to be common to all
branched compounds that do not form H-bonds. Substances with nets of hydrogen bonds in the liquid state have
lower n values, because motion of molecules then causes splitting of a larger part of intermolecular bonds. For
most organic substances, coefficient n is within the range 4– 4.5.
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