Balloon rubbing; where do the electrons go? If you rubbed a balloon with a towel, where would the electrons go: the balloon or the towel? Why?
I'm guessing the electrons would go to the object with a larger mass, but it's just a guess. :)
 A: This article on triboelectricity gives a triboelectric  series, listing materials according to whether they will expel electrons or acquire them , when rubbed or in contact.
Towel is not in there :) but cotton is, with 0 but it is more positive than rubber. So the answer is that the electrons will move to the balloon, if you manage to get cotton to give up its electrons :) . Did you do the experiment? A woolen towel would be much better. Maybe it was your hand that gave up the electrons after all.
This is what wikipedia has to say on the causes:

After coming into contact, a chemical
bond is formed between some parts of
the two surfaces, called adhesion, and
charges move from one material to the
other to equalize their
electrochemical potential. This is
what creates the net charge imbalance
between the objects. When separated,
some of the bonded atoms have a
tendency to keep extra electrons, and
some a tendency to give them away,
though the imbalance will be partially
destroyed by tunneling or electrical
breakdown (usually corona discharge).
In addition, some materials may
exchange ions of differing mobility,
or exchange charged fragments of
larger molecules.

Hence the need of a table.
