Gas laws

Source: Wikipedia. Pages: 24. Chapters: Acentric factor, Amagat's law, Avogadro's law, Boyle's law, Charles's law, Combined gas law, Compressibility factor, Dalton's law, Gay-Lussac's law, Graham's law, Henry's law, Magic number (chemistry), Partial pressure, Psychrometric constant, Redlich-Kwong equation of state, Van der Waals constants (data page), Van der Waals equation. Excerpt: The van der Waals equation is an equation of state for a fluid composed of particles that have a non-zero volume and a pairwise attractive inter-particle force (such as the van der Waals force). It was derived in 1873 by Johannes Diderik van der Waals, who received the Nobel prize in 1910 for "his work on the equation of state for gases and liquids". The equation is based on a modification of the ideal gas law and approximates the behavior of real fluids, taking into account the nonzero size of molecules and the attraction between them. The van der Waals isotherms: the model correctly predicts a mostly incompressible liquid phase, but the oscillations in the phase transition zone do not fit experimental data.The equation uses the following state variables: the pressure of the fluid p, total volume of the container containing the fluid V, number of moles n, and absolute temperature of the system T. One form of the equation is where is the volume of the container shared between each particle (not the velocity of a particle), is the total number of particles, and is Boltzmann's constant, given by the universal gas constant R and Avogadro's constant NA. Extra parameters are introduced: a is a measure for the attraction between the particles, and b is the average volume excluded from v by a particle. The equation can be cast into the better known form where is a measure of the attraction between the particles, is the volume excluded by a mole of particles. A careful distinction must be drawn between the volume available to a particle and the volume of a particle. In particular, in the first equation v refers to the empty space available per particle. That is, v is the volume V of the container divided by the total number nNA of particles. The parameter b, on the other hand, is proportional to the proper volume of a single particle - the volume bounded by the atomic radius. This is the volume to be subtracted from v because of the space taken up by one particle. In van de