Dependence of liquid and gas viscosity on the state parameters

The problem of the analytical description of liquid and gas viscosity versus the state parameters has been analysed. It was noted that the Kaplun equation, which unites the viscosity and the internal energy of a thermodynamic system, perfectly describes the viscosity in a wide range of the state parameters, but it can be used only if the state equation is available. It was shown that for any approach in different areas of the thermodynamic surface, a number of famous equations for liquid and gas viscosity can be obtained as a special case of this equation.