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The induced dipole forces appear from the induction (also termed polarization), which is the attractive interaction between a permanent multipole on one molecule with an induced (by the former di/multi-pole) 31 on another. [12] [13] [14] This interaction is called the Debye force, named after Peter J. W. Debye.
The intermolecular force was later conveniently described by the negative derivative of a pair potential function. For spherically symmetric particles, this is most simply a function of separation distance with a single characteristic length, σ {\displaystyle \sigma } , and a minimum energy, − ε {\displaystyle -\varepsilon } (with ε ≥ 0 ...
After the explanation of van der Waals forces by Fritz London, several scientists soon realised that his definition could be extended from the interaction of two molecules with induced dipoles to macro-scale objects by summing all of the forces between the molecules in each of the bodies involved.
Van der Waals forces include attraction and repulsions between atoms, molecules, as well as other intermolecular forces.They differ from covalent and ionic bonding in that they are caused by correlations in the fluctuating polarizations of nearby particles (a consequence of quantum dynamics [6]).
The terms perfect gas and ideal gas are sometimes used interchangeably, depending on the particular field of physics and engineering. Sometimes, other distinctions are made, such as between thermally perfect gas and calorically perfect gas, or between imperfect, semi-perfect, and perfect gases, and as well as the characteristics of ideal gases.
Intermolecular forces are the main constituent of changes in the enthalpy of a mixture. Stronger attractive forces between the mixed molecules, such as hydrogen-bonding , induced-dipole , and dipole-dipole interactions result in a lower enthalpy of the mixture and a release of heat. [ 6 ]
Deviations of the compressibility factor, Z, from unity are due to attractive and repulsive intermolecular forces. At a given temperature and pressure, repulsive forces tend to make the volume larger than for an ideal gas; when these forces dominate Z is greater than unity. When attractive forces dominate, Z is less than unity.
Many other thermodynamic processes will result in a change in volume. A polytropic process, in particular, causes changes to the system so that the quantity is constant (where is pressure, is volume, and is the polytropic index, a constant). Note that for specific polytropic indexes, a polytropic process will be equivalent to a constant ...