1. WARM UP Do ACT Prep Passage 5 – Reducing Pollution 5 minutes Start when the bell rings

2. Molecular Mass

3. Molecule A combination of bonded (ionic or covalent) atoms – Molecular formula (C 6 H 12 O 6 ) Actual number of atoms (6 C’s, 12 H’s, 6 O’s) – Empirical formula (CH 2 O) Simplest ratio

4. Molecular Mass Sum of mass of molecule’s atoms – Based on molecular formula (C 6 H 12 O 6 )

5. Molecular Mass o To calculate o = ∑ elements (mass x # of atoms) o (12 amu x 6) + (1 amu x 12) + (16 amu x 6) o 72 amu + 12 amu + 96 amu = 180 amu

6. Percent Composition Amount of an element in a molecule, by mass – Based on empirical formula (CH 2 O)

7. Percent Composition

8. o Calculating (use empirical formula) o = # of atoms x mass) x 100 empirical mass o %C = (1 x 12 amu) =.4 x 100 = 40% 30 amu

9. WRAP UP Calculate the molecular mass of: – Ammonia (NH 4 ) – Calcium phosphate (Ca 3 (PO 4 ) 2 )