1. Determining a Molecular Formulas:
The empirical formula of a chemical compound is C2H4NO. If its molar mass is g/mol, what is the molecular of the compound?
1st Find the mass of the empirical formula:
M (E:.F.) = 2(12.01) + 4(1.01)
= (4.04)
M (E:.F.) = g/mol

2. (The molecular formula is 4 times
2nd – Divide the molar mass (232.2 g/mol) by the mass of the empirical formula: = =
3.999
= 4
(The molecular formula is 4 times
greater than the empirical formula)
3rd Multiply the empirical formula by that #:
(C2H4NO) 4 =
C8H16N4O4
Molecular Formula

3. 1st – Find its Empirical Formula: C = H = O = = 5.450 mol = 2.997
2) Determine the molecular formula of a compound containing g of carbon, 5.45 g of hydrogen, and g of oxygen. Its molar mass is g/mol.
1st – Find its Empirical Formula:
C =
H =
O =
= mol
= 2.997
≈ 3
= mol
= 2.970
≈ 3
= 1
= mol
Empirical Formula
C3H3O

4. 2nd – Calculate the Empirical Formula Mass:
E.F = C3H3O
M(E.F.) = m (C) + m (H) + m (O)
= 3(12.01) + 3(1.01) + 1(16.00)
= g/mol
3nd – Divide the molar mass ( g/mol) by the
empirical formula mass: =
= 2
C6H6O2
(Molecular Formula)

5. 3) Succinic acid is composed of 40.68% carbon, 5.08% hydrogen, and 54.24% oxygen, its molar mass is g/mol. Determine its empirical and molecular formulas.
1st – Find its Empirical Formula:
= mol
= 1.000 C= H= O=
x 2
= 2
= mol
= 1.490
x 2
= 3
= mol
= 1.001
x 2
= 2
Empirical formula =
C2H3O2.

6. 2nd – Calculate the Empirical Formula Mass (C2H3O2 ):
M(E.F.) = m (C) + m (H) + m (O)
= 2(12.01) + 3(1.01) + 2(16.00)
= g/mol
3nd – Divide the molar mass (118.1 g/mol) by the empirical formula mass: =
= 2
4st – Multiply each subscript in the empirical formula by 2:
(C2H3O2) x 2 =
C4H6O4
Molecular Formula