Kinetic Theory

Definition: Kinetic Theory

Kinetic Theory

Noun

1. A theory that gases consist of small particles in random movement.

Specialty Definitions: Kinetic Theory

Domain	Definitions
Aerospace	The derivation of the bulk properties of fluids from the properties of their constituent molecules, their motions, and interactions. (references)
Physics	Theoretical approach which attempts to explain the behavior of physical systems using the assumptions that the systems are composed of large numbers of atoms/molecules/particles in vigorous motion, that energy and momentum are conserved in collisions of these particles, and that statistical methods can be applied to deduce the behavior of such systems. Kinetic theory has been applied to plasmas with considerable success, but is often computationally intensive. (references)
Source: compiled by the editor from various references; see credits.

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Specialty Definition: Kinetic theory

(From Wikipedia, the free Encyclopedia)

In physical chemistry, the kinetic theory of gases is a theory that explains the macroscopic properties of gases by consideration of their composition at a molecular level.

Postulates

The fundamental principles of the kinetic theory are given in the form of several postulates:

Gases are composed of molecules in constant random, motion. The moving particles constantly collide with each other and with the walls of the container.
The collisions between gas molecules are elastic.
The total volume of the gas molecules is neglible compared to the volume of the container.
The forces of attraction between the molecules are negligible.

The above postulates accurately describe the behavior of ideal gases. Real gases approach ideality under conditions of low density and high temperature.

Pressure

Pressure is explained by the kinetic theory as arising from the force exerted by collisions of gas molecules with the walls of the container. The derivation of the mathematical expression for pressure is given below:

Consider a gas with N molecules, each of mass m, enclosed in a cuboidal container of volume V. Suppose that a gas molecule collides with a wall of the container which is perpendicular to the x co-ordinate axis. Then the momentum lost by the particle and gained by the wall is given by

where v_x is the x-component of the initial velocity of the particle.
Now, force is the rate of change of momentum. The particle under consideration impacts with the wall once every 2l/v_x time units, where l is the length of the container. Therefore the force due to this particle is

and the total force on the wall is

where the summation is over all the gas molecules in the container. Since the particles are moving randomly in all directions, and since v² = v_x² + v_y² + v_z² for each particle, the expression for the total force becomes

This can be written as

where v_rms is the root mean square velocity of the gas. Therefore, pressure, the force per unit area, equals

where A is the area of the wall. Thus, we have the following expression for the pressure

This result is interesting and significant because it relates pressure, a macroscopic property, to the average (translational) kinetic energy per molecule (1/2 mv_rms²), which is a microscopic property.

Temperature

The above equation tells us that the product of pressure and volume is proportional to the average molecular kinetic energy. Further, the ideal gas equation tells us that this product is proportional to the absolute temperature. Putting the two together, we arrive at one important result of the kinetic theory: average molecular kinetic energy is proportional to the absolute temperature. The constant of proportionality is 3/2 times Boltzmann's constant, which is the ratio of the gas constant to Avogadro's number. This result is related to the equipartition theorem.

External links

http://www.phys.virginia.edu/CLASSES/252/kinetic_theory.html Kinetic theory of gases - A brief review
http://www.ucdsb.on.ca/tiss/stretton/chem1/gases9.html Introduction to the kinetic molecular theory of gases

Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Kinetic theory."

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Synonym: Kinetic Theory

Synonym: kinetic theory of gases (n). (additional references)

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Crosswords: Kinetic Theory

English words defined with "kinetic theory": Boltzmann ♦ kinetic theory of gases, kinetic theory of heat ♦ Ludwig Boltzmann. (references)

Specialty definitions using "kinetic theory": Energy Principle ♦ Gaussian law, Gauss'law ♦ Magnetic Reconnection, Maxwellian distribution, Microinstability ♦ normal distribution law ♦ Plasma Kinetic Equation. (references)

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Commercial Usage: Kinetic Theory

Domain	Title
Books	An Introduction to the Kinetic Theory of Gases and Magnetoplasmas (reference) Dynamics of Polymeric Liquids: Kinetic Theory (reference) Heat, Temperature, and Nuclear Radiation: Thermodynamics, Kinetic Theory, Heat Engines, Nuclear Decay, and Radon Monitoring (Units 16-18 & 28), Module 3, Workshop Physics(r) Activity Guide (reference) Kinetic Theory and Fluid Dynamics (reference) Kinetic Theory in the Expanding Universe (reference) (more book examples)
Source: compiled by the editor from various references; see credits.

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Expressions: Kinetic Theory

Expressions using "kinetic theory": kinetic theory of gases ♦ kinetic theory of heat. Additional references.
Source: compiled by the editor from various references; see credits.

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Frequency of Internet Keywords: Kinetic Theory

The following statistics estimate the number of searches per day across the major English-language search engines as identified by various trade publications. Hyperlinks lead to commercial use of the expression at Amazon.com.

Expression	Frequency per Day
kinetic theory	19
kinetic theory of gas	7
Source: compiled by the editor from various references; see credits.

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Anagrams: Kinetic Theory

Scrabble® Enable2K-Verified Anagrams
	Words within the letters "c-e-e-h-i-i-k-n-o-r-t-t-y"
	-4 letters: ethnicity, heterotic, intercity, theoretic, thereinto, thickener, tricotine.
	-5 letters: chinkier, coherent, coinhere, contrite, cytokine, enthetic, entirety, erection, eternity, hereinto, intertie, keynoter, knottier, neoteric, ornithic, reincite, reticent, retinite, tenorite, tetchier, thickety, thirteen, tonicity, trecento, trichite.
Source: compiled by the editor from various references; see credits. SCRABBLE® is a registered trademark. All intellectual property rights in and to the game are owned in the U.S.A and Canada by Hasbro Inc., and throughout the rest of the world by J.W. Spear & Sons Limited of Maidenhead, Berkshire, England, a subsidiary of Mattel Inc. Mattel and Spear are not affiliated with Hasbro.