1. Chem Catalyst - What is the atomic mass of: - Cl? - Fe? - KCl? - H 2 O?

2. Today’s Agenda: 1. Catalyst 2. Notes- Molar mass 3. HW: p. 296 # 7, 8; p. 303 #26,27

3. Molar Mass Periodic table gives mass in amu- same as the mass in grams of 1 mole of that substance [g/mol] For compounds: add mass of all elements to find total mass in g/mol.

4. Finding Molar Mass Find the molar mass of H 2 O 2 Find the molar mass of Al 2 O 3 Find the molar mass of Fe 2 O 3

5. Conversion: Moles to Mass - Multiply by (molar mass/ 1 mol) - Ex: What is the mass of 9.45 mol of Al 2 O 3 ?

6. Conversion: Mass to Moles - Multiply by (1 mol/ molar mass) - Ex: How many moles of iron (III) oxide are contained in 92.2g of Fe 2 O 3 ?

7. Summary Grams (mass)  moles Divide by molar mass Moles  grams (mass) Multiply by molar mass Atoms/molecules  moles Divide by Avogadro’s number (6.02x10 23 ) Moles  atoms/molecules Multiply by Avogadro’s number (6.02x10 23 )

8. Practice: 1. Calculate the mass, in grams, of 2.50 mol Fe(OH) 2 2. Find the mass of 3.00 mol of NaCl 3. Find the number of moles in 0.370 g of Boron. 4. Calculate the number of moles in 75.0 g of dinitrogen trioxide.