I guess that you mean: how could you melt the ice without warming it up?
You could put the ice in some salt water or sugar water or alcohol,
etc. The melting point of water in solutions like that is lower than in
pure water. So even if the solution is just as cold as the ice, unless
the ice will at least partly melt until the solution becomes more
dilute. When the ice melts, the solution will actually get colder. This
is how homemade ice-cream makers produce a bath of icewater that's
colder than the freezing point of pure water, which is needed to get
the ice cream to solidify.
If the ice is extremely cold to start with, there won't be any
non-frozen solution like that at the ice temperature, but heat will
flow from the water to the ice and melt it, assuming it doesn't freeze
in the process.
You can also squeeze on ice very very hard, which lowers its
melting point, perhaps below the ambient temperature. This happens
under the blades of ice skates -- a very thin layer of water forms
under the blades and lubricates the sliding of the blade on the ice.
In each case, thermal energy (heat) needs to be added to the ice
in order to melt it, even if that heat is added from cold surroundings.
It takes 80 calories per gram of energy to melt ice.
Mike W. (and Tom J.)
(published on 10/22/2007)
