Electrostatic forces and distance when considering changes in potentia

[Hereformore]

Question:

Relevant formulas:
kei + pei = kef + pef

U = kqq/r

Attempt at solution:

I thought that as distance increases potential energy would go down and so that energy would have to go to the kinetic energy of the gasses, so kinetic energy would increase.

This is consistent with the formula for electric potential energy but not consistent with the potential energy for gravity (wondering if there's a reason why/why it isn't consistent).

The book I am using says that since the molecules are attracted to each other, as they get farther away, their potential energy increases.

Is that because we're assuming the gas molecules are oppositely charged? So potential energy would be negative, and thus less negative when further away?

 

[TSny]

Hello, Hereformore.

Gas molecules generally have zero net charge. Nevertheless, they can still attract each other via electric forces! You can read about it here or here .