How would you use the kinetic theory to explain why a helium filled balloon "shrinks" when it is taken from a warm room to the outside on a cold day?

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Answer 1 · 2017-06-06T07:09:55

From kinetic theory, the pressure can be interpreted as, 2/3 the kinetic energy of molecules per unit volume.

#p = (2NE)/3V#

Also, from kinetic interpretation of temperature, the ideal gas molecules have their energy proportional to the absolute temperature.

Thus, #E = (3kT)/2#

Combining the two relations,

#pV# is proportional to #T#.

Then for a decrease in temperature #T#, then #V# and #p# decrease.

This explains why the balloon shrinks when the temperature decreases.