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Kinetic Theory of Gases

The molecules of an ideal gas have a range of speeds. When an individual molecule collides with another one its speed and direction changes, but as long as the temperature is constant, the distribution of speeds remains the same.The root mean square speed crms of the molecules is the square root of the mean of the squares of the speeds of all the individual molecules. If the temperature is increased, crms increases and the distribution is flatter and broader.The kinetic theory equation for an ideal gas is: pV = ⅓Nmcrms2. The mean kinetic energy of a molecule ½mcrms2 = 3/2kT where k = R/NA.

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Specification: Edexcel Physics (9PH0), A-level, Topic 9: Thermodynamics, statements 147 and 148. Topic: Gases.

Key terms in this lesson

background radiation
Ionising radiation present in the environment at all times, from sources such as cosmic rays, rocks and radon gas.

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