kinetic energy and speed

[MowgliR]

Two different gases at same temperature have the same average kinetic energy, BUT different average speeds ( lighter one is going faster).

How does kinetic energy differ from speed when talking about gases?

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[UCB05]

Two different gases at same temperature have the same average kinetic energy, BUT different average speeds ( lighter one is going faster).

How does kinetic energy differ from speed when talking about gases?

Different gas particles have different masses. If two gases have the same average kinetic energy, the heavier one has lower average speed and the lighter one has higher average speed.

 

[yappy]

Kinetic Energy is realted to speed (velocity) by the formula:

KE = ½*m*v²

Notice how the same KE value may be acheived by different mass and velocity values.

 

[rmm30]

Its pretty intuitive actually. Lighter gas molecules are faster than heavy. Think Kinetic Energy = 1/2 mass * velocity ^2. This equation is familiar right? The thing to remember that mass and velocity are indirectly proportional. Meaning as one gets smaller the other gets larger. So if 2 gasses have the same Ke, but different masses, mathematically you can see that the one with the smaller mass will have the larger velocity.

another equation that you will probably come across is the root mean sq velocity : rms= sqrt (3RT/M) where T is temp, R is gas constant, and M is molar mass. Here again the larger the mass the slower the speed of the gas.