Elysian12

2+ Year Member
May 20, 2015
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Pre-Dental
Question states:

Which statement is false?
a) Kr has a lower average speed than Ne at the same temperature
b) The molecules of a gas undergo many collisions with each other and with the walls of the container
c) Deviations from the ideal gas law are greater at low temperature and high pressure
d) All molecules of an ideal gas have the same kinetic energy at constant temperature
e) All are true

I do not understand why the Answer is D and not E. The explanation talks about a Boltzmann Distribution Curve which I have never heard in my life. Could someone explain it a different way. I thought all gases have the same KE at a constant temperature, but different average velocities at a constant temperature (as stated in A).

Thank you
 
May 17, 2008
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Dentist
The average KE of all ideal gas at the same temperature is the same. Keep in mind that is the average, not necessarily the KE of every single gas particle. If you were to actually graph the KE of every single molecule of an ideal gas at a certain temperature you would see a distribution almost like a bell curve: some with the average KE, some lower, some higher, etc. This curve (when graphing the speed of the ideal gas particles - distribution is the same) is called a Boltzmann distribution curve. So it is false to say that all molecules of a gas are proportional to the absolute temperature, because they are only all proportional on average. It is this specific wording that makes the choice incorrect.
 
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