Perfect gasses temperature vs kinetic energy per molecule

AI Thread Summary
Temperature is directly related to the kinetic energy of gas molecules, with the average kinetic energy per molecule being proportional to temperature. The ideal gas law (PV = nRT) connects pressure, volume, and temperature, but kinetic energy must account for motion in three dimensions. The average kinetic energy per molecule is expressed as KE = (3/2)PV/n, which includes translational motion. Additionally, the relationship can be represented using Boltzmann's constant, where KE = (3/2)NkT, emphasizing that each mode of motion contributes to the total energy. Understanding these principles clarifies the connection between temperature and kinetic energy in ideal gases.
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Homework Statement


I have been wondering about temperature and it's relation to kinetic energy I didn't study thermodynamics so I hope that replies could be simplified.I am trying to think about the perfect gas law to relate kinetic energy per molecule to temperature, and I want to know if I have a somewhat close understanding.


Homework Equations


PV=RnT


The Attempt at a Solution


PV=RnT
I am thinking that P*V expresses the energy stored in the gas molecules since P =F/A and V=m^3 so P*V=F*m which is the unit of work so W=RnT
and since the work expresses the change of kinetic energy
deltaK= RnT
(delta K)/n = RT
so this gives me the intuition that since the change of kinetic energy per molecule is equal to a constant times the temperature so its proportional to it. I didn't study thermodynamics and only basics of physical chemistry so probably there are things I missed but is my intuition at least correct?
 
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Your intuition (or subconsciously-remembered info) is in the right direction
... but the PV is related to the Work that can be done on the Area (2-d),
not the entire molecule KE , which comes from motion in all 3 dimensions.
So, the KE per molecule (an average, of course) is actually 3/2 * PV/n .
... this is translational KE of the molecule's center-of-mass, not including
rotational KE and vibrational KE of the atoms relative to that c.o.m.

It is more traditional to write KE = 3/2 N kT , with N being the number of molecules,
and k is Boltzmann's konstant = 1.38E-23 J/K , which is R/N_avagadro .
The "3" signifies that there are 3 modes of motion which contribute to this KE ; every mode (including means rotations and vibrations also, if they occur) in a molecule holds E(average) = 1/2 kT .
 
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