Chem Catalyst- What is the atomic mass of:

- Cl?

- Fe?

- KCl?

- H2O?

Today’s Agenda:1. Catalyst2. Notes- Molar mass3. HW: p. 296 # 7, 8; p. 303 #26,27

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.

Finding Molar Mass• Find the molar mass of H2O2

• Find the molar mass of Al2O3

• Find the molar mass of Fe2O3

Conversion: Moles to Mass- Multiply by (molar mass/ 1 mol)

- Ex:

What is the mass of 9.45 mol of Al2O3?

Conversion: Mass to Moles- Multiply by (1 mol/ molar mass)

- Ex:

How many moles of iron (III) oxide are contained in 92.2g of Fe2O3?

SummaryGrams (mass) moles

Divide by molar mass

Moles grams (mass)

Multiply by molar mass

Atoms/molecules moles

Divide by Avogadro’s number (6.02x1023)

Moles atoms/molecules

Multiply by Avogadro’s number (6.02x1023)

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.