الملخص

Equations  of state are used for the evaluation of pressure effects on solid (Alkali halides) at room temperature and high temperature up to melting point, Thermodynamic properties such as   ,  of alkali halide (NaCl-B1) at  high pressure and room temperature have been evaluated and the results are compared with experimental data and gave good results up to 5 GPa but beyond it the results of these  equations of state diverge from experimental data while Bardeen equation of state gave good agreement with experimental data , the effect of high pressure and high temperature on vibration energy of atoms ( )and on heat capacity at constant volume ( ) of (NaCl-B1) are calculated by using Debye Model and gave good agreement with the theory, also thermal volume and pressure ( ),( ) and thermal expansion coefficient ( ) are calculated  by using thermal equation of state by Kumar . Finally, melting curve of (NaCl-B1) was calculated by using Kumar thermal equation of state with Lindeman equation the results were compared with experimental data. Also inter ionic distance at melting ( ) for (NaCl-B1) was calculated by two ways, first by using lattce potential energy and second by using Anderson equation, and compared    with data of other researcher and a good fitting was observed.