Percent Composition and Chemical Formulas

Chapter 10.3

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 = %100compound theof massmolar

compound of mol 1in element of mass

Percent Composition – Example

Calculate the percent composition of titanium dioxide (TiO2)

Percent Composition – Example

Calculate the percent composition of ammonium chloride (NH4Cl)

Percent Composition Extension – Example

Calculate the mass of hydrogen in 15.2 g ammonium chloride.

Empirical Formulas

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

Molecular Formulas

A molecular formula is a multiple of the empirical formula

Empirical Formula - CH2OMolecular Formula – C2H4O2 (Acetic Acid)Molecular Formula – C3H6O3 (Lactic Acid)Molecular Formula – C4H8O4 (1,4-dioxane-2,3-diol)