Kinetic energy of gas molecules

[akimhaneul]

So I know that average kinetic energy of gas molecules at a certain temperature is same no matter what the gas is.

I was just wondering why each individual gas molecules cannot have same kinetic energy. I heard that it's more of a distribution. Why is it like this even though the gas molecules are all under same condition?


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[sazerac]

So I know that average kinetic energy of gas molecules at a certain temperature is same no matter what the gas is.

I was just wondering why each individual gas molecules cannot have same kinetic energy. I heard that it's more of a distribution. Why is it like this even though the gas molecules are all under same condition?

https://en.m.wikipedia.org/wiki/File:Translational_motion.gif

The Wikipedia article on the "Kinetic Theory of Gases" has this cool introductory pic, above, that explains it as well as 1000 words can.

All the gas molecules could have the same kinetic energy, but it is statistically very unlikely.

 

[aldol16]

I was just wondering why each individual gas molecules cannot have same kinetic energy. I heard that it's more of a distribution. Why is it like this even though the gas molecules are all under same condition?

This is a question of statistical mechanics. It's related to the idea of an average in statistics. This is beyond the scope of the MCAT because stat mech isn't tested but at the most fundamental level, molecules are all defined by probabilities. That's what a wave function is. But at a higher level of analysis, each individual molecule has a certain probability of existing in a certain state. You might say that a 0.1% chance of having a kinetic energy of 100 arbitrary units is pretty low, but when you're talking about moles of molecules, you'll inevitably end up with some in that category.