Average Kinetic Energy

[JohnTulisa]

On the DAT destroyer 2016,

#64 explanation states that all molecules of an ideal gas have the same kinetic energy at constant temperature is FALSE.

#44 However, states that all gases have the same average kinetic energy

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[super frank]

Key word here is all molecules. All molecules of a specific ideal gas (molecules of Cl2, for example) do not have the same kinetic energy. Each individual molecule has a different kinetic energy from one another, resulting in an average kinetic energy for the gas as a whole. I believe it's called the Boltzmann distribution or something. There is a graph that adequately describes what I am trying to explain.

At a specific temperature all gases (Cl2 vs. He) will have the same average kinetic energy since kinetic energy is dependent on temperature. However, not all individuals molecules of Cl2 have the same kinetic energy as each other, and likewise not all He molecules have the same kinetic energy as each other. They come out to an average, which is equal, if temperature is equal. In addition, remember that although Cl2 and He may have the same average kinetic energy at the same temperature, the average velocities are different. He is much lighter, and therefore will travel faster/effuse more rapidly (to make up the difference in 1/2mv^2). It is also less dense due to the same principle (d = PM/RT).

 

[dentalstudent2021]

On the DAT destroyer 2016,

#64 explanation states that all molecules of an ideal gas have the same kinetic energy at constant temperature is FALSE.

#44 However, states that all gases have the same average kinetic energy

soooooooooooooooooooooooooooooooooooooooooooo...

all molecules have the same average kinetic energy at constant/same temperature.