1. 10.3 Percent Composition and Empirical Formula

2. Fertilizer

3. Percent Composition is the percent mass of each element in a compound.
% composition of a compound is always the same
% mass of element = mass of element in 1 mol compound x 100%
molar mass of compound

4. Practice Solve: What is the percent composition of propane? C3H8?
You’re gearing up for the Superbowl and have decided to grill some Franks using your propane grill.
Equation:
% comp = mass element in 1 mol x 100% molar mass compound
Solve:
What is the percent composition of propane? C3H8?

5. Calculate the % composition of these compounds
Ethane (C2H6)
Sodium hydrogen sulfate ( NaHSO4)

6. Calculate the % Nitrogen in these fertilizers
3. NH3
4. NH4NO3

7. Empirical and Molecular Formulas
Empirical formula: gives the lowest whole-number ratio of atoms of the elements in a compound.
The molecular formula tells the actual # of each kind of atom present in the molecule.
Hydrogen Perioxide: H2O HO H2O2
Empirical Formula
Molecular Formula
Chemical Formula

8. Which of the following compounds have the same empirical formula?
A. CO2 and SO4
B. C7H14 and C10H20
C. C4H10 and C10H4
D. C6H12 and C6H14

9. The lowest whole-number ratio of elements in a compound is called the
A. empirical formula B. molecular formula C. binary formula D. representative formula

10. What is the percent by mass of Carbon in acetone, C3H6O?
A. 20.7% B. 62.1% C. 1.61% D. 30.0%

11. What is the percent by mass of chromium in BaCrO4?
D. 25.2%