1. Percent Composition and Chemical Formulas
Chapter 3.3

2. Percent Composition
It is sometimes useful to know a compound’s composition in terms of the masses of its elements. This is known as percent mass.
% mass =

3. Percent Composition – Example
Calculate the percent composition of titanium dioxide (TiO2)

4. Percent Composition – Example
Calculate the percent composition of ammonium chloride (NH4Cl)

5. Percent Composition Extension – Example
Calculate the mass of hydrogen in 15.2 g ammonium chloride.

6. Empirical Formulas
Empirical formulas are the lowest whole-number ratio of the atoms in a compound

7. Molecular Formulas
A molecular formula is a multiple of the empirical formula
Empirical Formula - CH2O
Molecular Formula – C2H4O2 (Acetic Acid)
Molecular Formula – C3H6O3 (Lactic Acid)
Molecular Formula – C4H8O4 (1,4-dioxane-2,3-diol)

8. HW #39
Read Pages 60-67
Problems 62, 63, 65, 69, 73, 78