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The ideal gas equation can be rearranged to give an expression for the molar volume of an ideal gas: = = Hence, for a given temperature and pressure, the molar volume is the same for all ideal gases and is based on the gas constant: R = 8.314 462 618 153 24 m 3 ⋅Pa⋅K −1 ⋅mol −1, or about 8.205 736 608 095 96 × 10 −5 m 3 ⋅atm⋅K ...
The following table lists the Van der Waals constants (from the Van der Waals equation) for a number of common gases and volatile liquids. [ 1 ] To convert from L 2 b a r / m o l 2 {\displaystyle \mathrm {L^{2}bar/mol^{2}} } to L 2 k P a / m o l 2 {\displaystyle \mathrm {L^{2}kPa/mol^{2}} } , multiply by 100.
Liquid hydrogen (H 2 (l)) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H 2 form. [4] To exist as a liquid, H 2 must be cooled below its critical point of 33 K. However, for it to be in a fully liquid state at atmospheric pressure, H 2 needs to be cooled to 20.28 K (−252.87 °C; −423.17 °F). [5]
The molar volume of any ideal gas may be calculated at various standard reference conditions as shown below: V m = 8.3145 × 273.15 / 101.325 = 22.414 dm 3 /mol at 0 °C and 101.325 kPa; V m = 8.3145 × 273.15 / 100.000 = 22.711 dm 3 /mol at 0 °C and 100 kPa; V m = 8.3145 × 288.15 / 101.325 = 23.645 dm 3 /mol at 15 °C and 101.325 kPa
In 1766, Henry Cavendish was the first to recognize hydrogen gas as a discrete substance, by naming the gas from a metal-acid reaction "inflammable air". He speculated that "inflammable air" was in fact identical to the hypothetical substance " phlogiston " [ 65 ] [ 66 ] and further finding in 1781 that the gas produces water when burned.
Note that the especially high molar values, as for paraffin, gasoline, water and ammonia, result from calculating specific heats in terms of moles of molecules. If specific heat is expressed per mole of atoms for these substances, none of the constant-volume values exceed, to any large extent, the theoretical Dulong–Petit limit of 25 J⋅mol ...
The volume of gas increases proportionally to absolute temperature and decreases inversely proportionally to pressure, approximately according to the ideal gas law: = where: p is the pressure; V is the volume; n is the amount of substance of gas (moles) R is the gas constant, 8.314 J·K −1 mol −1
where 1/n 0 is the volume occupied by each molecule in the gas phase, and πℓd 2 /4 is the volume of the cylinder made by the molecule in its trajectory between two collisions. However, the true volume of each molecule is given by πd 3 /6, and so n 0 πd 3 /6 is the volume occupied by all the molecules not counting the empty space between them.