Why Do Gases Need Same Speed for Thermal Equilibrium?

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For two gases to be in thermal equilibrium, they must have the same average molecular kinetic energy, not necessarily the same average molecular speed. This is due to the relationship between temperature and kinetic energy as defined by the kinetic theory of gases. When gases of different molecular weights are mixed, the lighter molecules will move faster than the heavier ones, leading to differing speeds. Therefore, thermal equilibrium is achieved when the average kinetic energy is equal, despite variations in molecular speed. Understanding this distinction is crucial in thermodynamics and gas behavior.
Himanshu_6174
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When two gases are
mixed, if they are to be in thermal equilibrium, they must have the
same average molecular speed. Why or why not?
 
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Himanshu_6174 said:
When two gases are
mixed, if they are to be in thermal equilibrium, they must have the
same average molecular speed. Why or why not?

Actually, they have the same average molecular kinetic energy. If the two gases have different molecular weights, then then they won't have the same average speed; the more massive molecules will be moving slower than the lighter molecules.
 
Thanks stevendaryl, I was thinking the same. Just wanted to confirm :)
 

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