D. Entropy rises with increasing mass, other things being
equal. We can show this by comparing the entropies of the diatomic
halogens, in order of increasing mass,
or by looking at a series of molecules with increasing numbers
of atoms.
This is an important principle, but a hard one to account for without
quantum mechanics. Simple quantum theory tells us that as the size
and mass of an atom or molecule increase, the spacings between its
energy levels decrease. We have used this principle constantly in
discussing delocalized electrons in molecules. A large and massive
object with a certain total energy has more quantum states available
to it, so W is larger and S = k In W is greater. For the nonquantum
mechanically inclined, a bull in a china shop creates more disorder
than a mouse.
|