1. Molecular Formula
Acetic Acid
Glucose
Formaldehyde

2. Steps Find the empirical formula
Calculate the molar mass of the empirical formula
Multiplier = ( 𝑚𝑜𝑙𝑎𝑟 𝑚𝑎𝑠𝑠 𝑔𝑖𝑣𝑒𝑛 𝑚𝑜𝑙𝑎𝑟 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑒𝑚𝑝𝑖𝑟𝑖𝑐𝑎𝑙 𝑓𝑜𝑟𝑚𝑢𝑙𝑎 )
Multiply empirical formula subscripts by the multiplier to get the molecular formula

3. Example 1
A compound composed of 40.68% carbon, 5.08% hydrogen and 54.24% oxygen has a molar mass of g/mol. Determine the empirical and molecular formula.
E.F. = C2H3O2
40.68 g C mol C
12.01 g C
= mol C
3.387
= mol C ×2 = 2
Molar Mass:
C: ×2
H: 1.01 ×3
+ O: ×2
59.05g
5.08 g H mol H
1.01 g H
= mol H
3.387
= mol H ≈ 1.5 ×2 = 3
118.1 g
59.05g
54.24 g O mol O
16.00 g O
= mol O
3.387
= mol O ×2 = 2
= 2
M.F. = C4H6O4

4. Example 2
A compound has a molar mass of g/mol and contains 77.87% C, 11.76% H, and 10.37% O. Determine the empirical and molecular formulas.
M.F. = C30H54O3