1. MOLAR MASS
The molar mass is the mass, in grams, of one mole (6.02  1023 particles) of an element (ion), a covalent molecule or a formula unit.
molar mass (MM) gram atomic mass (gam) molecular weight (MW) gram molecular mass (gmm)
formula mass (FM) gram formula mass (gfm)
formula weight (FW)

2. MASS of one MOLE
Gram atomic mass (gam): the atomic mass (the mass in one mole of a substance) of an element expressed in grams.
Gram molecular mass (gmm): the atomic mass of one mole of a molecular compound.
Gram formula mass (gfm): the sum of the atomic masses of the atoms that are in the formula of a compound.

3. gam, gfm, gmm examples:
Problem: Give the gram atomic mass of hydrogen.
Solution: H = 1H = 1(1.01) = 1.01 g/mol
Problem: Give the gram molecular mass of hydrogen.
Solution: H2 = 2H = 2(1.01) = 2.02 g/mol
Problem: Find the gram formula mass for H2SO4.
Solution: H2SO4 = 2H + 1S + 4O
= 2(1.01) (16.00) = g/mol

4. Molar Mass … a.k.a. Molecular Weight (MW)
molar mass = mass of 1 mole of substance
Molar mass can be determined by adding up the atomic masses from the periodic table (atomic mass goes to 2 decimal places).

5. MW Example 1: = 1C + 4H = 12.01 + 4(1.01) = 16.05 g CH4/mol CH4
Find the MW of CH4.
= 1C + 4H
= (1.01)
= g CH4/mol CH4

6. MW Example 2: =Mg + 2O + 2H =24.31 + 2(16.00) + 2(1.01)
Find the MW of Mg(OH)2.
=Mg + 2O + 2H
= (16.00) + 2(1.01)
=58.33 g Mg(OH)2 /mol Mg(OH)2

7. MW Example 3: Find the MW of MgSO4∙7H2O. =Mg + S + 4O + 7(H2O)
= (16.00) + 7( )
= g MgSO4∙7H2O /mol MgSO4∙7H2O

8. Calculations:
Use Mole Map to help calculate

9. Mole Mass Calculations
1 mole = molar mass (MW) in grams
Mass
MOLE

10. Mass Example 1:
How many grams are in 7.20 moles of dinitrogen trioxide?
dinitrogen trioxide = N2O3
MW of N2O3 = 2N + 3O = 2(14.01) + 3(16.00) = g/mol
1 mole = g N2O3

11. MW of Fe2O3 = 2Fe + 3O = 2(55.85) + 3(16.00) = 159.70 g/mol
Mass Example 2:
Find the number of moles in 92.2 g of iron(III) oxide.
iron(III) oxide = Fe2O3
MW of Fe2O3 = 2Fe + 3O = 2(55.85) + 3(16.00) = g/mol
1 mole = g Fe2O3

12. Make sure you write out all work and include all units!!
Practice Worksheet
Do #1-10 on Mole and Mass WS
Make sure you write out all work and include all units!!