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Physical
vs. Chemical Changes
Learn
the difference between physical and chemical changes.
Introduction
Physical changes and chemical changes have much in common
in that you are looking at similar kinds of results. The difference
is whether the appearances or differences that you see are
from a change in condition of the materials or from a change
in what materials are present.
Distinguish
That's the kind of thing you need to look for to distinguish
between a chemical reaction and a physical change. It takes
a good observation to make that distinction. Sometimes it
is very difficult to make that distinction and in some cases
even chemists get into arguments sometimes over what constitutes
a physical change and a chemical one.
Scientific
Arguments
For example, when salt dissolves into water, some people say
that it is simply a physical change because if you evaporate
the water, you have the salt back again. Other people argue
that there is a chemical change because the material present
in solution has different properties than separated pure water
and separated pure salt. The solution will conduct electricity
and the pure materials will not. So, there are cases where
the distinction between the changes gets kind of blurred.
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