EQUIPARTITION OF ENERGY
have seen in Section 9.2.1 that the average kinetic energy of a molecule moving
in x direction is
when the motion is in y direction,
According to kinetic theory, the
average kinetic energy of system of molecules in thermal equilibrium at
temperature T is uniformly distributed to all degrees of freedom (x or y or z
directions of motion) so that each degree of freedom will get 1/2 kT of energy.
This is called law of equipartition of energy.
kinetic energy of a monatomic molecule (with f=3) =
kinetic energy of diatomic molecule at low temperature (with f = 5)
kinetic energy of a diatomic molecule at high temperature (with f =7)
kinetic energy of linear triatomic molecule (with f = 7) =
kinetic energy of nonlinear tri atomic molecule (with f = 6) =
relation CP − CV = R connects the two specific heats for
one mole of an ideal gas.
law of energy is used to calculate the value of CP − CV
and the ratio between them γ = CP / CV.
γ is called adiabatic exponent.
kinetic energy of a molecule
one mole, the molar specific heat at constant volume
Average kinetic energy of a diatomic molecule at low temperature = 5/2kT
energy of one mole of gas
the total energy is purely kinetic)
one mole Specific heat at constant volume
of a diatomic molecule at high temperature is equal to 7/2RT
that the CV and CP are higher for diatomic
molecules than the mono atomic molecules. It implies that to increase the
temperature of diatomic gas molecules by 1°C it require more heat energy than
that according to kinetic theory model of gases the specific heat capacity at
constant volume and constant pressure are independent of temperature. But in
reality it is not sure. The specific heat capacity varies with the temperature.
the adiabatic exponent γ for mixture of μ 1 moles
of monoatomic gas and μ2 moles of a diatomic gas at normal