1. Unit 6: Chemical Quantities
Chapter 10: The Mole and Molar Mass

2. The Mole and Molar Mass
Atomic Mass is expressed in amu (atomic mass units)
Where can you find the amu of an element?
Periodic Table
Molar Mass
One mole of any substance is equal to the atomic mass expressed in grams
1 mol = molar mass (g/mol) = atomic mass (g)
Gram Atomic Mass (GAM) = Elements
Gram Formula Mass (GFM) = Ionic Compounds
Gram Molecular Mass (GMM) = Molecular Compounds

3. The Mole and Molar Mass Calculating Molar Mass
Count the number of atoms in the substance.
Find the atomic mass of each element from the Periodic Table. Round each one to one decimal place.
Multiply the number of atoms of each element by the atomic mass of that element.
Add the values together to get the total molar mass for that substance.

4. The Mole and Molar Mass Calculating Molar Mass Example 1:
What is the molar mass of iron (III) oxide, Fe2O3?
1) # of Atoms 2) Atomic Mass 3) Multiply
2 Fe x 2 = 111.6
3 O x 3 =
Fe2O g/mol

5. The Mole and Molar Mass Calculating Molar Mass
Determine the mass in grams of the following substances:
O2 =
NaCl =
C3H8 =

6. The Mole and Molar Mass Conversions
You can use the molar mass to convert from moles to grams and vice versa
1 mol = molar mass (g/mol)
Conversion factors are… or
Mass (grams)
1 mole
1 mol
Mass (grams)

7. The Mole and Molar Mass Practice:
What is the mass of 9.45 mol of Aluminum Oxide?
Find the formula for Aluminum Oxide
Find the molar mass of the compound
Then use the conversion 1 mole = mass of the compound
9.45 mol Al2O g Al2O = 964 g Al2O3
1 mol Al2O3

8. The Mole and Molar Mass Practice :
How many moles are of iron (III) oxide are contained in 92.2 g?
92.2 g Fe2O mol Fe2O3 = mol Fe2O3
159.6 g Fe2O3