How Does Room Temperature Affect Air Molecule Energy from Winter to Summer?

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SUMMARY

The discussion focuses on the relationship between room temperature and the kinetic energy of air molecules, as described by the kinetic molecular theory (KMT). At 5°C, the average kinetic energy is calculated to be 34 J/mole, while at 25°C, it increases to approximately 37 J/mole, resulting in a difference of 3 J per mole. For a room measuring 3m x 3m x 4m, the total energy difference between winter and summer is calculated to be 4573 J. The conversation clarifies that this energy is not a measure of power, as energy is retained by gas molecules until collisions occur, and thus cannot be equated to a constant power output.

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  • Kinetic Molecular Theory (KMT)
  • Gas Laws (PV=nRT)
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skepticwulf
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According to KMT, Avarage kinetic energy of 1 mole gas is=(3/2) x R x T
So , in winter in my cold room ,
the gases have Kea=34J/mole (T=5oC)

and in summer that figure climbs to, -roughly- 37J/mole, (T=25oC)
Difference is , 3J per mole.

If my rooms dimensions are 3m x 3m x 4m, volume is 36m^3, so
n is = PV/RT=(1)(36.000)/(0.082)(15+273) (avg temp of 15oC taken to compute number of moles)
n=1524 mole ==> 3J x 1524= 4573J That's the difference of Energy between winter and summer for my room.

So, does that mean the air molecules in my room carries 4573J more energy in summer compared to winter?

How can I put time factor? Can I say they carry that per second?
Power=E/t=4573/1=4573 Watts??
Can I assume they hit my body constantly it's as if 4573W heater is in the room and warms me up??
 
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The number of moles is not the same. The room is not a sealed container but one in equilibrium with the atmospheric pressure.
If you do the calculation right you will see that the total energy is independent of temperature but dependent of pressure.
Time does not come into the picture.
 
Can you elaborate on that pls?
 
The number of moles in a room of volume V, at pressure p and temperature T is
N=pV/RT
If you multiply this by the energy per mole, u=3/2 RT, the temperature simplifies. There is nothing more to "elaborate".
 
skepticwulf said:
Can I say they carry that per second?

No, the energy is not 'per second'. Energy per second would be power, and would imply that the gas is losing or gaining that much energy per second. A gas molecules with X joules of kinetic energy will retain that energy until a collision causes it to either give up or gain energy. As the molecule bounces around over time, it will randomly gain or lose energy with each bounce. If the gas is in equilibrium then all of these collisions tend to cancel themselves out and you can assign an average value.
 
nasu said:
The number of moles in a room of volume V, at pressure p and temperature T is
N=pV/RT
If you multiply this by the energy per mole, u=3/2 RT, the temperature simplifies. There is nothing more to "elaborate".
Thank you!, you're such a nice person.
 
You are welcome. :smile:
 

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