1. UNIT 5A Chapter 10: Chemical Quantities Molar Mass ABClark-Grubb

2. What is Molar Mass? Element: The atomic mass of an element expressed in grams is the mass of one mole of the element. Element: The atomic mass of an element expressed in grams is the mass of one mole of the element. Example: 16.0 g Oxygen = 1 mol Oxygen Example: 16.0 g Oxygen = 1 mol Oxygen 12.0 g Carbon = 1 mol Carbon Use your periodic table, find the molar masses of the following elements… Use your periodic table, find the molar masses of the following elements… Chlorine Chlorine Mercury Mercury Iron Iron 35.5 g/mole 200.6 g/mole 55.8 g/mole

3. Compound: The sum of the atomic masses of each atom in the compound. Compound: The sum of the atomic masses of each atom in the compound. Example: SO 3 Example: SO 3 1. 1. Find the molar masses of each element. 2. Then multiply by the number of atoms of each element. 3. Finally, add the masses together. S = 32.1 g O = 16.0 g X 1 X 3 = 32.1 g/mole = 48.0 g/mole 80.1 OR 80.1 g SO 3 = 1 mol SO 3 g/mole

4. Find the Molar Mass of a Compound Find the molar mass of aluminum sulfate: Al 2 (SO 4 ) 3 Al = 27.0 g S = 32.1 g O = 16.0 g X 2 X 3 = 54.0 g/mole = 96.3 g/mole + 342.3 OR 342.3 g Al 2 (SO 4 ) 3 = 1 mol Al 2 (SO 4 ) 3 X 12= 192.0 g/mole g/mole

5. Try these examples… Find the molar mass of PCl 3 P = 31.0 g Cl = 35.5 g X 1 X 3 = 31.0 g = 106.5 g + 137.5 137.5 g PCl 3 = 1 mol PCl 3 Find the molar mass of H 2 CO 3 H = 1.0 g C = 12.0 g O = 16.0 g X 2 X 1 = 2.0 g = 12.0 g + 62.0 62.0 g H 2 CO 3 = 1 mol H 2 CO 3 X 3= 48.0 g g/mole