1. Molar Mass

2. Why 6.02 X 1023?
Couldn’t Avogadro have picked an easier number to work with??
It has been determined experimentally that there are 6.02 X 1023 carbon atoms in 12 g of C-12.
1 atom of C-12 has a mass of 12 u
1 mole of C-12 has a mass of 12 g
The mole allows us to easily convert from atomic mass units (microscopic) into grams (macroscopic)

3. 1 C-12 atom has a mass of 12 u
1 mole of C-12 has a mass of 12 g
OR 12 g/mole
1 O-16 atom has a mass of 16 u
1 mole of O-16 has a mass of 16 g
OR 16 g/mole
This applies to molecules as well:
1 molecule of H2O = 2 X1.01 u u = u
1 mole of H2O = g
OR g/mole

4. Molar Mass
The mass of 1 mole of any substance is called its molar mass and it is written in units of g/mol
E.g. The molar mass of potassium is g/mol (i.e 6.02X 1023 atoms of K have a mass of g)
* Don’t forget about diatomic molecules!!
The molar mass of an oxygen atom (O) is g/mol. The molar mass of oxygen molecules (O2) is g/mol (16.00 X 2)

5. E.g. What is the molar mass of ammonium phosphate?

6. Practice What does a mole looks like? Worksheet P. 170 #7-13