1. Empirical Formula

2. The empirical formula is the simplest whole number ratio between atoms in a compound.
It is determined experimentally by measuring the mass of the elements that combine to form a compound.

3. A compound is found to contain 63. 55 % Ag, 8. 23 % N and 28. 24 % O
A compound is found to contain % Ag, 8.23 % N and % O. Calculate the empirical formula.
Assume that you have 100 g- that means g Ag, 8.23 g N, and g O
When in doubt- mole it out!
63.55 g Ag x mole g
= mol
= 1
mol
8.23 g N x mole g
= mol
AgNO3
= 1
mol
28.24 g O x mole
16.0 g
= mol
= 3
mol

4. A compound is found to contain 50. 07 % Cu, 16. 29 % P and 33. 64% O
A compound is found to contain % Cu, % P and 33.64% O. Calculate the empirical formula.
Double
Rearrange
50.07 g Cu x 1 mole
63.5 g
= mol
= 1.5
= 3
mol
16.29 g P x 1 mole
31.0 g
= mol
= 1
= 2
Cu3P2O8
mol
Cu3(PO4)2
33.64 g O x 1 mole g
= mol
= 4
= 8
mol
Only do this for ionic compounds
Not for covalent!
Braniac Alkali Metals

5. A compound is found to contain 46. 08 % C, 27. 0 % N and 27. 0 % O
A compound is found to contain % C, 27.0 % N and 27.0 % O. Calculate the empirical formula.
46.08 g C x 1 mole
12.0 g
= mol =
x 7
= 16
1.688 mol
27.0 g N x 1 mole
14.0 g
= mol =
x 7
= 8
1.668 mol
27.0 g O x 1 mole g
= mol
= 1
x 7
= 7
1.688 mol
C16N8O7
Braniac Alkali Metals