1. Molar Mass

2.  A compound is a collection of bonded together. Ethanol, CH 3 CH 2 OH, is made up of : carbon atoms, hydrogen atoms, and oxygen atom, 2 6 1 atoms _________

3. Molar Mass of CH 3 CH 2 OH How many molecules of ethanol are in one mole of ethanol? How many atoms of carbon are in one mole of ethanol? Of hydrogen? Of oxygen? _____________________________ 2 x (6.02 x 10 23 ) atoms C !! 6 x (6.02 x 10 23 ) atoms H !! 1 x (6.02 x 10 23 ) atoms O !! 6.02 x 10 23 molecules EtOH

4. Molar Mass of CH 3 CH 2 OH  How many moles of carbon are in one mole of ethanol?  Of hydrogen?  Of oxygen? _________________________ 2 moles of carbon!! ___________________________ 6 moles of hydrogen!! 1 mole of oxygen!! ________________________

5. Molar Mass  In general, in a chemical formula, the number of atoms of an element in a molecule of a compound is the same as the number of moles of that element in a mole of the compound. C 6 H 12 O 6 Fe 2 O 3  Now let’s relate mass to moles in a chemical formula.

6. Molar Mass of CH 3 CH 2 OH  How many grams in 1 mole of carbon? 12.01g  In 1 mole of hydrogen? 1.008g  In 1 mole of oxygen? 16.00g

7. Molar Mass of CH 3 CH 2 OH  Now let’s calculate the molar mass of ethanol: 2 moles C 12.01g C = 24.02 g 1 mole C 6 moles H 1.008g H = 6.05 g 1 mole H 1 moles O 16.00g O = 16.00 g 1 mole O 46.07g Molar Mass of EtOH = 46.07g/mole

8. Molar Mass  “The Molar mass of a compound is the sum of the atomic masses for each element in the compound, multiplied by the number of times the element occurs in the compound”.

9. Molar Mass - Practice  Calculate the molar mass of: NaCl = Al 2 O 3 = C 6 H 12 O 6 = Na 3 PO 4 = 23.01g Na/mol + 35.45g Cl/mol = 58.45 g/mole 2(26.98gAl/mol) + 3(16.00gO/mol) = 101.96 g/mole 6(12.01gC/mol) + 12(1.008gH/mol) + 6(16.00gO/mol) = 180.16 g/mole 3(23.01gC/mol) + (30.97gP/mol) + 4(16.00gO/mol) = 117.98 g/mole