1. Empirical Formula

2. Definition A formula that shows the simplest whole-number ratio of the atoms in a compound Ex: H 2 O Not an Ex: H 4 O 2

3. Percent to mass, Mass to mole, Divide by small, Multiply 'til whole. Poem for Steps **If you have a 100g sample, the percent composition is the same as the mass

4. Example #1 Determine the empirical formula for a compound with the percent composition of 40.00% carbon, 6.72% hydrogen, and 53.28% oxygen.

5. Example #2 Determine the empirical formula for methyl acetate, which has the following chemical analysis: 48.64% carbon, 8.16% hydrogen and 43.20% oxygen.

6. Example #3 A 50.0 g sample of a compound contains 18.25 g Na, 19.05 g O, and 12.70 g S. Determine the empirical formula.

7. Example #4 A 50.0 g sample of a compound contains 2.52 g Be, 5.01 g Al, 15.68 g Si, and 26.97 g O. Determine the empirical formula.