1. Quantities in Chemistry The Mole and Molar Mass

2. Mole Review A Mole is a unit of measurement in chemistry. It represents 6.02 x 10 23 of an entity. One mole of sodium is 6.02 x 10 23 atoms of sodium. The symbol for mole is “n”. The unit for mole is “mol” 6.02 x 10 23 is also known as Avogadro’s number.

3. How do we measure out 1 mol? Do you count out 6.02 x 10 23 atoms in the lab? Do you use special equipment? Can you measure it as a volume? Can you measure it as a mass?

4. Amazing! 1 mole = amu of the element in grams For Example: 1 mol of H atoms = 1 mol of O atoms = 1 mol of C atoms = 1 mol of Na atoms = 1 mol of Au atoms = 1.01g 16.0g 12.01g 22.99g 197.0g

5. Molar Mass Molar Mass (MM) is the mass (in grams) of one mole of a substance. The formula for molar mass is For example, Hydrogen’s molar mass = 1.01 g/mol

6. Molar Mass of Compounds The molar mass of a compound is equal to the sum of the molar masses of the atoms in the molecules or ions in the compound. For example, the molar mass of water is: MM H 2 O = 2(MM H ) + (MM O ) = 2(1.01g/mol) + 1(16.0g/mol) =18.02 g/mol

7. Example: Find the molar mass of H 2 CO 2 MM H 2 CO 2 = 2(MM H ) + (MM C ) +2(MM O ) = 2(1.01g/mol) + (12.00g/mol) + 2(16.0g/mol) =46.02 g/mol