**critical properties**of chemical compounds are gathered, where critical temperature and critical pressure are tabled with the chemical formula and its respective molecular weight, the critical temperature is given 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, the equation of state developed by J.D. Van der Waals requires critical temperature and critical pressure to calculate the constants "a" and "b" values. This equation of state is used for knowing the behaviour of real gas that deviates from the 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. The gas temperature will be shown in the results section. Similarly for the calculating pressure for know temperature.