- #1
apache
when you equate the two formulas for ideal gases, one is evetually left with a formula to calculate the ke. of the ideal gas (3/2kt i think) how come the ke is independent of the mass of the molecule ?
Hi apache,Originally posted by apache
thanks guys,
i think i finally got it !
Standard postulate here is "In thermal equilibrium energy is equally distributed among all available degrees of freedom (equipartition)", so temperature T is defined in such way that each degree has in the average kT/2 amount of energy. If a molecule is monoatomic, it has 3 degrees only(x,y,z), thus <E>=3kT/2, if diatomic then it has two more (rotational) degrees, thus <E>=5kT/2, and so on.Originally posted by Tyger
The temperature is basically the mean energy per unit quantum, in this case atoms or molecules are the "quanta" involved, (this isn't the standard definition of quantum) and the pressure is the mean energy per unit volume...
In non-ideal gasses some of the energy is tied up in rotational modes, which is why they have differing ratios of specific heat.