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Thermodynamic properties Phase behavior ... Gas properties Std enthalpy change of formation, ... Methane vapor pressure vs. temperature.
Methane (US: / ˈ m ɛ θ eɪ n / METH-ayn, UK: / ˈ m iː θ eɪ n / MEE-thayn) is a chemical compound with the chemical formula CH 4 (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas.
Some constants, such as the ideal gas constant, R, do not describe the state of a system, and so are not properties. On the other hand, some constants, such as K f (the freezing point depression constant, or cryoscopic constant ), depend on the identity of a substance, and so may be considered to describe the state of a system, and therefore ...
Near the critical point, all these properties change into the exact opposite: water becomes compressible, expandable, a poor dielectric, a bad solvent for electrolytes, and mixes more readily with nonpolar gases and organic molecules. [4] At the critical point, only one phase exists. The heat of vaporization is zero.
The ideal gas model has been explored in both the Newtonian dynamics (as in "kinetic theory") and in quantum mechanics (as a "gas in a box"). The ideal gas model has also been used to model the behavior of electrons in a metal (in the Drude model and the free electron model), and it is one of the most important models in statistical mechanics.
In thermodynamic terms, this is a consequence of the fact that the internal pressure of an ideal gas vanishes. Mayer's relation allows us to deduce the value of C V from the more easily measured (and more commonly tabulated) value of C P : C V = C P − n R . {\displaystyle C_{V}=C_{P}-nR.}
In thermodynamics, the reduced properties of a fluid are a set of state variables scaled by the fluid's state properties at its critical point. These dimensionless thermodynamic coordinates, taken together with a substance's compressibility factor , provide the basis for the simplest form of the theorem of corresponding states .
For gases, departure from 3 R per mole of atoms is generally due to two factors: (1) failure of the higher quantum-energy-spaced vibration modes in gas molecules to be excited at room temperature, and (2) loss of potential energy degree of freedom for small gas molecules, simply because most of their atoms are not bonded maximally in space to ...