Kinetic
Molecular Theory
Blogger no.3:
Basic Concepts
The gas laws developed by Boyle, Charles, and
Gay-Lussac are based upon empirical observations and describe the behavior of a
gas in macroscopic terms, that is, in terms of properties that a person can
directly observe and experience. An alternative approach to understanding the
behavior of a gas is to begin with the atomic theory, which states that all
substances are composed of a large number of very small particles (molecules or
atoms). In principle, the observable properties of gas (pressure, volume,
temperature) are the consequence of the actions of the molecules making up the
gas.
The Kinetic Molecular Theory of Gases begins with five
postulates that describe the behavior of molecules in a gas. These postulates
are based upon some simple, basic scientific notions, but they also involve
some simplying assumptions. In reading a postulate, do two things. Firstly ,try
to understand and appreciate the basic physical idea embodied in the postulate. This idea will ultimately be important in understanding the macroscopic
properties of the gas in terms of the behavior the microscopic molecules making
up the gas. Second, identify possible weakness or flaws in the postulates.
Inaccurate predictions by a theory derive from flawed postulates used in the
derivation of the theory.
Postulates
·
A gas consists of a collection of small particles
traveling in straight-line motion and obeying Newton's Laws.
·
The molecules in a gas occupy no volume (that is, they
are points).
·
Collisions between molecules are perfectly elastic (that
is, no energy is gained or lost during the collision).
·
There are no inter molecular force of attraction or repulsion between the molecules.
·
The average kinetic energy of a molecule is 3kT/2.
(T is the absolute temperature and k is the Boltzmann constant.)
We hope that understanding Kinetic molecular theory now would be much more easier with the help of our blog. :)
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