1. Section 3.1 The Mole and Molar Mass

2. The Mole and Molar Mass In this section…
Connecting the atomic and real worlds
The mole
Elemental molar mass
Compound molar mass
Conversions between atoms, moles, and mass

3. How do we relate atoms and molecules to the real world?
1 “mole” of atoms or molecules fills a small handful.

4. 1 mole = 6.02 x 1023 atoms or molecules
1 mole of Cu, Al, S, K2Cr2O7, H2O and CuCl22H2O

5. 1 mole = 6.02 x 1023 atoms or molecules
1 mole of elements Cu, Al, S,

6. 1 mole = 6.02 x 1023 atoms or molecules
1 mole compounds K2Cr2O7, H2O and CuCl22H2O

7. The mole as a conversion factor
1 mol element = 6.02 x 1023 atoms of that element

8. The mole as a conversion factor
1 mol element = 6.02 x 1023 atoms of that element
moles atoms
1.95 mol Al
atoms moles
4.68 x 1023 Cu atoms

9. The mole as a conversion factor
1 mol element = 6.02 x 1023 atoms of that element
moles atoms
When doing these calculations,
does it matter which element
is used?
atoms moles

10. Elemental molar mass elemental molar mass = mass of 6.02 x 1023 atoms
elemental molar mass = atomic weight on periodic table,
in grams per mole

12. Molar mass
1 mol Al =
1 mol F =

13. Molar mass as a conversion factor
1 mol Al = molar mass Al = g Al
moles grams
1.95 mol Al
1.95 mol Al

14. Molar mass as a conversion factor
1 mol Cu = molar mass Cu = g Cu
grams moles
49.4 g Cu
49.4 g Cu

15. Compound molar mass
compound molar mass = mass of 6.02 x 1023 molecules
compound molar mass = sum of atomic weights of atoms
in the molecule
SO2

16. Converting between grams and moles for a compound
Step 1. Determine molar mass
Step 2. Use molar mass as a conversion factor

17. Molar mass as a conversion factor
SO2 = g/mol
moles grams
What is the mass of a 1.45 mol sample of SO2?
grams moles
What amount, in moles, of SO2 does a 212-g sample represent?

18. Multistep Problems
How many oxygen atoms are present in a 212-g sample of SO2?
Problem Map: