Search results
Results From The WOW.Com Content Network
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.
The attractive force draws molecules closer together and gives a real gas a tendency to occupy a smaller volume than an ideal gas. Which interaction is more important depends on temperature and pressure (see compressibility factor). In a gas, the distances between molecules are generally large, so intermolecular forces have only a small effect.
The van der Waals equation, named for its originator, the Dutch physicist Johannes Diderik van der Waals, is an equation of state that extends the ideal gas law to include the non-zero size of gas molecules and the interactions between them (both of which depend on the specific substance). As a result the equation is able to model the phase ...
The black curve corresponds to the Lennard-Jones potential. The Mie potential is an interaction potential describing the interactions between particles on the atomic level. It is mostly used for describing intermolecular interactions, but at times also for modeling intramolecular interaction, i.e. bonds. The Mie potential is named after the ...
t. e. In chemistry and physics, cohesion (from Latin cohaesiō 'cohesion, unity'), also called cohesive attraction or cohesive force, is the action or property of like molecules sticking together, being mutually attractive. It is an intrinsic property of a substance that is caused by the shape and structure of its molecules, which makes the ...
Boyle temperature. The Boyle temperature, named after Robert Boyle, is formally defined as the temperature for which the second virial coefficient, , becomes zero. It is at this temperature that the attractive forces and the repulsive forces acting on the gas particles balance out. This is the virial equation of state and describes a real gas.
For more complex gases the agreement is not as good, most likely due to the neglect of attractive forces. [13] Indeed, the Lennard-Jones model , which does incorporate attractions, can be brought into closer agreement with experiment (albeit at the cost of a more opaque T {\displaystyle T} dependence; see the Lennard-Jones entry in table 1). [ 14 ]
The mean intermolecular interaction of a Lennard-Jones particle strongly depends on the thermodynamic state, i.e., temperature and pressure (or density). For solid states, the attractive Lennard-Jones interaction plays a dominant role – especially at low temperatures. For liquid states, no ordered structure is present compared to solid states.