Nonlinearity acoustic parameters from equation of state of liquid sodium under pressure

In the present paper, the expressions for acoustical parameter and nonlinearity parameter are obtained based on thermodynamic relations from an equation of state with a power law form. Both parameters for liquid Sodium are calculated under high pressure along the isothermal lines by using the available thermodynamic data and numeric derivations. The relation between the isochoric acoustical parameter and internal pressure is derived and the corresponding approximation at low pressure condition is discussed. The present results show nonlinearity parameter is a nonlinear function of pressure along the isothermal lines in liquid sodium. The calculated values are found to be very close to the experimental measurements and quasi-thermodynamic theory at melting point at ambient condition. Furthermore, several other thermodynamic quantities are also presented.