DETERMINATION OF
EMPIRICAL FORMULA
The empirical formula of a
compound represents the
simplest whole number ratio of
the elements in that compound.
EXAMPLE # 1
A real-life example of an empirical
formula is glucose (C₆H₁₂O₆), a
sugar found in many foods.
The molecular formula for glucose
is C₆H₁₂O₆, which shows that for
every 6 carbon atoms, there are 12
hydrogen atoms and 6 oxygen
atoms. However, the empirical
formula simplifies this ratio to
CH₂O, which shows that for every
carbon atom, there are two
hydrogen atoms and one oxygen
atom in the simplest ratio.
So, even though glucose has the
molecular formula C₆H₁₂O₆, its
empirical formula is CH₂O.
A sample of a compound contains 5.30 g of
nitrogen (N) and 14.70 g of oxygen (O).
What is the empirical formula of the
compound?
Mass of nitrogen (N) = 5.30 g
Mass of oxygen (O) = 14.70 g
STEP 1:
OBTAIN THE MASS OF EACH ELEMENT
STEP 2:
CONVERT THE MASS OF EACH ELEMENT
TO MOLES
• moles of nitrogen:
5.30 g
14.01 g/mol =
/
/
0.378mol of N
• moles of oxygen:
14.70g = 0.919mol of O
16.00 g/mol
/
/
Data
from
periodic
table
Notice that grams (g) were
canceled because they appear in
both the numerator and the
denominator.
