From Wikipedia,
the free encyclopedia.
In
chemistry, the empirical
formula of a chemical is a
simple expression of the relative
number of each type of
atom (called a
chemical element) in it. An
empirical formula makes no
reference to
isomerism, structure, or
absolute number of atoms.
Empirical formulas are the
standard for ionic compounds, such
as CaCl2, and for
macromolecules, such as SiO2.
The term empirical refers
to the process of
elemental analysis, a
technique of
analytical chemistry used to
determine the relative percent
composition of a pure chemical
substance by element.
In contrast, the
molecular formula identifies
the absolute number of atoms of
such element to be found in each
discrete molecule of that
compound.
For example,
hexane could have a structural
molecular formula of CH3CH2CH2CH2CH2CH3,
implying that it has a straight
chain structure, 6
carbon atoms, and 14
hydrogen atoms. The hexane
molecular formula is C6H14.
And the empirical formula for the
same molecule would be C3H7
showing a C:H ratio of 3:7.
