Theory of Viscosity

Abstract

LET us treat flow as a rate process¹, that is, assume when two layers of molecules in a liquid slide past each other, then the molecules of the layers travel in the same layer from one equilibrium position to another. During this passage, each molecule has to break the ‘bonds’ between it and its nearest (and perhaps certain of its remoter) neighbours, so that the process can be represented as a unimolecular reaction. If the specific reaction-rate constant of this reaction is k', then by applying the theory of the transition state, the coefficient of viscosity η should be where λ₁, λ₂, λ₃ are the intermolecular distances in the three-space co-ordinates, λ the distance between the two equilibrium positions, k is the Boltzmann constant and T the absolute temperature.