1. MOLECULAR FORMULA whole number multiple of the empirical formula
need: empirical formula
MM of molecular formula

2. MOLECULAR FORMULA What is the empirical formula of
a cmpd that 27.3% C and 72.7% O?

3. MOLECULAR FORMULA
The molecule’s MM is g/mol. Calc. the molecular formula:
1. Find MM of the empir. formula.

4. MOLECULAR FORMULA
The molecule’s MM is g/mol. Calc. the molecular formula:
2. Divide molecular MM by empirical MM.

5. MOLECULAR FORMULA
The molecule’s MM is g/mol. Calc. the molecular formula:
3. Multiply all elements by the whole # to get the molec. formula.

6. Calculate molecular formulas:
Molar
Mass
Empirical
Formula
Molecular
Formula
60 g/mole
CH4N
C2H8N2
181.5 g/mol
C2HCl
C6H3Cl3