1. It’s time to learn about...

2. Stoichiometry

3. Stoichiometry : Mole Ratios to Determining Grams of Product At the conclusion of our time together, you should be able to: 1. Review the conversion of particles or grams to moles 2. Determine mole ratios from a balanced chemical equation 3. Determine the amount of product produced when given the amount of reactants

4. Review the Molar Mass of Compounds The molar mass (MM) of a compound is determined by adding up all the atomic masses for the molecule (or compound) ◦ Ex. Molar mass of CaCl 2 ◦ Avg. Atomic mass of Calcium = 40.08g ◦ Avg. Atomic mass of Chlorine = 35.45g ◦ Molar Mass of calcium chloride = 40.08 g/mol Ca + (2 X 35.45) g/mol Cl  110.98 g/mol CaCl 2 17 Cl 35.45 Cl 20 Ca 40.08a

5. Practice Calculate the Molar Mass of calcium phosphate ◦ Formula = ◦ Masses elements: ◦ Molar Mass = 310.18 g Ca 3 (PO 4 ) 2

6. Calculations Moles molar mass Avogadro’s number Grams Moles Particles Everything must go through Moles!!!

7. Flowchart Atoms or Molecules Moles Mass (grams) Divide by 6.02 X 10 23 Multiply by 6.02 X 10 23 Multiply by atomic/molar mass from periodic table Divide by atomic/molar mass from periodic table

8. Cookies and Chemistry…Huh!?!? Just like chocolate chip cookies have recipes, chemists have recipes as well Just like chocolate chip cookies have recipes, chemists have recipes as well Instead of calling them recipes, we call them reaction/equations Instead of calling them recipes, we call them reaction/equations Furthermore, instead of using cups and teaspoons, we use moles Furthermore, instead of using cups and teaspoons, we use moles Lastly, instead of eggs, butter, sugar, etc. we use chemical compounds as ingredients Lastly, instead of eggs, butter, sugar, etc. we use chemical compounds as ingredients

9. Chocolate Chip Cookies!! 1 cup butter 2 eggs 1/2 cup white sugar 1 teaspoon salt 1 cup packed brown sugar 1 teaspoon vanilla extract 2 1/2 cups all-purpose flour 1 teaspoon baking soda 2 cups semisweet chocolate chips Makes 3 dozen How many eggs are needed to make 3 dozen cookies? How much butter is needed for the amount of chocolate chips used? How much brown sugar would I need if I had 1½ cups white sugar?

10. Mole Ratios These mole ratios can be used to calculate the moles of one chemical from the given amount of a different chemical Are obtained by comparing the coefficients in a balanced chemical equation.

11. Chemistry Recipes – Page 11 Looking at a reaction tells us how much of something you need to react with something else to get a product (like the cookie recipe) Be sure you have a balanced reaction before you start!  _Cl 2 + _Ag  _AgCl  If there are 5 moles of Ag, how many moles of Cl 2 ?

12. Practice – Page 11 __Fe(OH) 3  __Fe 2 O 3 + __H 2 O If 6 moles react: a)How many moles of iron (III) oxide? b)How many moles of water?

13. Practice – Page 12 _SiO 2 + _HF  _SiF 4 + _H 2 O Mole ratios? a)25 moles of SiO 2 converts to how many moles of SiF 4 ?

14. “Mole Relationships” Lab Lead (II) nitrate and sodium iodide  ???? Which test tube will produce the max amount? Test #1Test #2Test #3Test #4Test #5 1.5:4.52:43:34:24.5:1.5

15. Mass-Mass Conversions Most often we are given a starting mass and want to find out the mass of a product we will get (called theoretical yield) or how much of another reactant we need to completely react with it (no leftover ingredients!) Now we must go from grams to moles, to mole ratios, and back to grams of the compound we are interested in.

16. Mass-Mass Conversion – Page 17 __Fe + __S 8  __FeS How many grams of iron are required to make 86.7g of FeS. How many moles of sulfur are needed?

17. Practice Mass-Mole-Mass – Page 17 #2 _CS 2 + _Cl 2  _CCl 4 + _S 2 Cl 2 If 17.6g of carbon disulfide react with an excess of chlorine, how many grams of disulfur dichloride will result?

18. Practice Mass-Mole-Mass – Page 17 #3 _P 4 + _O 2  _P 4 O 10 How many grams of phosphorous will react with 25g of oxygen?

19. Stoichiometry : Mole Ratios to Determining Grams of Product Let’s see if you can: 1. Review the conversion of particles or grams to moles 2. Determine mole ratios from a balanced chemical equation 3. Determine the amount of product produced when given the amount of reactants

20. Mass-Mole-Molecules: Determine the number of molecules in 73 g of water 73 g H 2 O # H 2 O molecules = x 1 mol H 2 O 18.02 g H 2 O = 2.4 x 10 24 molecules H 2 O x 6.02x10 23 molecules 1 mol H 2 O

21. Try this one: Calculate the mass in grams of iodine required to react completely with 0.50 moles of aluminum. Al + I 2  AlI 3 2 Al + 3 I 2  2 AlI 3 = 190 g I 2 0.50 mol Al x 3 mol I 2 2 mol Al x 253.80 g I 2 1 mol I 2

22. Try this one: Calculate the mass in grams of iodine required to react completely with 0.50 g of aluminum. Al + I 2  AlI 3 2 Al + 3 I 2  2 AlI 3 = 7.1 g I 2 x 3 mol I 2 2 mol Al x 253.80 g I 2 1 mol I 2 0.50 g Al x 1 mol Al 26.98 g Al