1. Chemical Composition
Mole (mol) – The number equal to the number of carbon atoms in grams of carbon.
Avogadro’s number – The number of atoms in exactly 12 grams of pure 12C; x 1023.
One mole of anything contains x 1023 units of that substance.

2. Molar mass – The mass in grams of 1 mol of the substance.
Molar Mass of an element is the mass in grams of x atoms.
Molar Mass of an compound is the mass in grams of x molecules or units.

3. % Composition = grams of element
of element by mass grams of compound X 100
% Composition = molar mass of element__
of element by molar mass of compound X 100
molar mass

4. Hydrate – Molecule with water attached to crystalline structure. Ex
Hydrate – Molecule with water attached to crystalline structure. Ex. CuSO4 * 5H2O
molar mass of H2O
% Comp. H2O = molar mass of X 100
hydrate compound

5. Percent to mass Mass to mole Divide by small Multiply 'til whole
Empirical Formula – Expressed the smallest whole-number ratio of the atoms present in a compound.
Percent to mass Mass to mole Divide by small Multiply 'til whole

6. Molecular Formula – The exact formula of a molecule, giving the types of atoms and the number of each.
Compare empirical formula mass to known molar mass.
Molecular formula = (empirical formula)n
n = molar mass
empirical formula mass