Chemistry The effect of temperature and mass on the distribution of speeds in a gas.

You can use the two applets below to explore the effect of changing temperature and changing molar mass on the shape of the Maxwell distribution of speeds, the most probable speed and the mean speed. Note that:

 
  • the most probable speed is at the maximum of the distribution curve

  • the mean speed is slightly to the right of the most probable speed: it has a slightly greater value

 

Effect of temperature:

The model is set up to display the speed distribution of nitrogen molecules at different temperatures.

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Effect of mass:

The model is set up to display the speed distribution of different molecules at a constant temperature of 1000 K.

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You should have found the following concerning the effect of temperature and mass variables on the shape of the speed distribution:

 
  • the higher the temperature the higher the average speed and the broader the range of speeds

  • the greater the mass the lower the average speed and the narrower the range of speeds

 

The basis of Maxwell's work was the kinetic model and this model allowed not only the derivation of speed distribution, but also the distribution of kinetic energies.