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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 ...
Specific volume is commonly applied to: Molar volume; Volume (thermodynamics) Partial molar volume; Imagine a variable-volume, airtight chamber containing a certain number of atoms of oxygen gas. Consider the following four examples: If the chamber is made smaller without allowing gas in or out, the density increases and the specific volume ...
The molar volume of gases around STP and at atmospheric pressure can be calculated with an accuracy that is usually sufficient by using the ideal gas law. 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
The molar volume of a mixture can be found from the sum of the excess volumes of the components of a mixture: = (+ ¯). This formula holds because there is no change in volume upon mixing for an ideal mixture. The molar entropy, in contrast, is given by
In this equation, usually is called the attraction parameter and the repulsion parameter (or the effective molecular volume). While the equation is definitely superior to the ideal gas law and does predict the formation of a liquid phase, the agreement with experimental data for vapor-liquid equilibria is limited.
For instance, solid NaCl has a volume of 27 cm 3 per mole, but the apparent molar volume at low concentrations is only 16.6 cc/mole. In fact, some aqueous electrolytes have negative apparent molar volumes: NaOH −6.7, LiOH −6.0, and Na 2 CO 3 −6.7 cm 3 /mole. [ 4 ]
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 following table lists the Van der Waals constants (from the Van der Waals equation) ... 1 L 2 atm/mol 2 = 0.101325 J·m 3 /mol 2 = 0.101325 Pa·m 6 /mol 2.