**critical properties**of chemical compounds are gathered, where critical temperature and critical pressure are tabled with chemical formula and its respective molecular weight, critical temperature is give in two units namely degree Rankine and degree Kelvin similarly the critical pressure of all chemical compounds are given in Psia and Bar units. These values can be used for calculation in thermodynamic systems. For instance, equation of state developed by J.D. Van der Waals require critical temperature and critical pressure to calculate the constants "a" and "b" values. This equation of state is used for knowing the behavior of real gas that deviates from ideal gas equation of state calculation. Solver for calculating temperature and pressure of a real gas is given below. By entering the critical temperature and pressure of a gas, constants "a" and "b" are calculated. To know the temperature of 1 kmol of known volume and gas pressure, enter the respective values in the white space and press enter. Gas temperature will be shown in results section. Similarly for the calculating pressure for know temperature.