Critical Points for some Substances
Critical points of some common substances like air, argon, helium and more
At the critical point there is
- no change of state when pressure is increased or if heat is added
At the critical point the liquid and gas phase can't be distinguished and there is no point referring to liquid or gas.
At the critical point the physical properties of the liquid and gaseous states are identical.
For states above the critical point the gas is supercritical.
Substance | Temperature (K) | Pressure (atm) | Specific Molar Volume (cm3/gmol) | Compressibility Z = Pv/RT |
---|---|---|---|---|
Acetylene - C2H2 | 309.5 | 61.6 | 113 | 0.274 |
Air | 132.63 | 37.36 | 92.35 | |
Argon - Ar | 150.72 | 47.99 | 75 | 0.291 |
n-Butane - C4H10 | 425.17 | 37.47 | 255 | 0.274 |
Carbon Dioxide - CO2 | 304.20 | 72.90 | 94 | 0.275 |
Carbon Monoxide - CO | 132.91 | 34.529 | 93 | 0.294 |
Ethane - C2H6 | 305.48 | 48.20 | 148 | 0.285 |
Ethylene - C2H4 | 283.06 | 50.50 | 124 | 0.270 |
Helium - He | 5.19 | 2.26 | 58 | 0.308 |
Hydrogen - H2 | 33.24 | 12.797 | 65 | 0.304 |
Methane - CH4 | 190.7 | 45.8 | 99 | 0.290 |
Nitrogen - N2 | 126.2 | 33.54 | 90 | 0.291 |
Oxygen - O2 | 154.78 | 50.14 | 74 | 0.292 |
Propane - C3H8 | 370.01 | 42.1 | 200 | 0.277 |
Sulfur Dioxide - SO2 | 430.7 | 77.8 | 122 | 0.269 |
Water - H2O | 647.27 | 218.167 | 56 | 0.230 |
Note! - the critical point is not the same as the triple point.
- 1 cm3/gmol = 10-3 liter/mol
Related Topics
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Thermodynamics
Work, heat and energy systems.
Related Documents
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Cryogenic Fluids and Liquefied Gas Properties
Cryogenic properties as density, boiling points and heat of evaporation for fluids like hydrogen, methane, oxygen, nitrogen, fluorine and helium. -
Helium - Thermophysical Properties
Chemical, Physical and Thermal Properties of Helium - He. -
Substances Triple Points
Triple points for common substances. -
Water vs. Steam - Critical and Triple Points
Critical point is where vapor and liquid are indistinguishable and triple point is where ice, water and vapor coexist in thermodynamic equilibrium.