Viscosity of gas: molecular diameter calculation

The viscosity of a gas is related to its resistance to flow. It is determined by the transfer speed of the flow from the layers that move faster than those that move slower. The so-called perspiration method is a method adopted for the measurement of gas viscosity. In the approach used, the flow speed of the gas is measured by monitoring the evacuation of a container by means of a capillary tube under a constant differential pressure. Using the kinetic theory, it is possible to estimate the molecular diameter of the gas.