1. Avogadro’s number, the mole, molarity, molar mass
Chemical Quantities
Avogadro’s number, the mole, molarity, molar mass

2. The Mole
A unit of measurement that allows chemists to “count” atoms, ions, and molecules using their mass.
Because these representative particles are too small to physically count.
1 mole is Avogadro’s number of anything. Compare to 12 eggs = 1 dozen eggs 1 mol = 6.02 x 1023

3. Calculating Molar Mass
Elements: average atomic mass = molar mass
Example – carbon: 12 amu = 12 g, sulfur: 32 amu = 32 g
Compounds: sum of average atomic mass = molar mass = 1 mole of compound
Example – H2O: 18.0 g H: 1 amu, O: 16 amu 2(1 amu) + 16 amu = 18 amu = 18 g H2O = 1 mol H2O
average atomic mass = 1 mole = 6.02 x 1023 molecules
1 mol H2O = 18 g = 6.02 x 1023 molecules H2O
1 mol H = 1 g, 1 mol O = 16 g