2. Stoichiometry

3. The Mole A counting unit A counting unit Similar to a dozen, except instead of 12, it’s 602,000,000,000,000,000,000,000 Similar to a dozen, except instead of 12, it’s 602,000,000,000,000,000,000,000 6.02 X 10 23 (in scientific notation) 6.02 X 10 23 (in scientific notation) This number is named in honor of Amedeo Avogadro (1776 – 1856) This number is named in honor of Amedeo Avogadro (1776 – 1856)

4. The mass of 1 mole (in grams) The mass of 1 mole (in grams) Equal to the numerical value from periodic table, or add the mass of the atoms together for a molecule Equal to the numerical value from periodic table, or add the mass of the atoms together for a molecule 1 mole of C atoms= 12.0 g 1 mole of C atoms= 12.0 g 1 mole of Mg atoms =24.3 g 1 mole of O 2 molecules =32.0 g Molar Mass

5. Molar Mass of Compounds The molar mass (MM) of a compound is determined the same way, except you add up all the atomic masses for the molecule The molar mass (MM) of a compound is determined the same way, except you add up all the atomic masses for the molecule Ex. Molar mass of CaCl 2 Ex. Molar mass of CaCl 2 Avg. Atomic mass of Calcium = 40.08g Avg. Atomic mass of Calcium = 40.08g Avg. Atomic mass of Chlorine = 35.45g 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 Molar Mass of calcium chloride = 40.08 g/mol Ca + (2 X 35.45) g/mol Cl  110.98 g/mol CaCl 2 20 Ca 40.08a 17 Cl 35.45 Cl

6. Formula Units Formula Units A term to describe an ionic or covalent compound. A term to describe an ionic or covalent compound.

7. Flowchart Formula Units 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 Atoms Multiply by number of atoms in formula Divide by number of atoms in formula

8. Practice Calculate the Molar Mass of calcium phosphate Calculate the Molar Mass of calcium phosphate Formula = Formula = Masses elements: Masses elements: Ca: 3 Ca’s X 40.1 = Ca: 3 Ca’s X 40.1 = P: 2 P’s X 31.0 = P: 2 P’s X 31.0 = O: 8 O’s X 16.0 = O: 8 O’s X 16.0 = Molar Mass = Molar Mass = Ca 3 (PO 4 ) 2 120.3 g 62.0 g 128.0 g 120.3g + 62.0g +128.0g310.3 g/mol

9. molar mass Avogadro’s number Grams Moles particles molar mass Avogadro’s number Grams Moles particles Everything must go through Moles!!! Calculations

10. Atoms/Molecules and Grams How many moles of Cu are present in 35.4 g of Cu? How many atoms would that be?

11. Learning Check! What is the mass (in grams) of 1.20 X 10 24 molecules of glucose (C 6 H 12 O 6 )? Hint: convert to moles first, then to grams.

12. Practice 1. How many atoms in total are indicated in (a) NH 4 NO 3 (b) Mg 3 (PO 4 ) 2 2. How many formula units (molecules) are in 3 moles of NH 4 NO 3 ? How many atoms is that? 3. How many moles are in 5.64 x 10 21 molecules of Mg 3 (PO 4 ) 2 ? 4.How many moles are in 9.52 x 10 31 atoms of Mg 3 (PO 4 ) 2 ?

13. Mass to atoms (and back) 5. How many H atoms are in 2.3g of water? 6. Determine the mass of 6.7 x 10 12 molecules of water. 7. Determine the number of atoms contained in 1.2 g of NaCl

14. Complete Mole Calculations Worksheet Complete Mole Calculations Worksheet Read pg 47-50 Read pg 47-50 Complete #5-11, pg 52

15. Stoichiometry

16. Chocolate Chip Cookies!! 1 cup butter 1/2 cup white sugar 1 cup packed brown sugar 1 teaspoon vanilla extract 2 eggs 2 1/2 cups all-purpose flour 1 teaspoon baking soda 1 teaspoon salt 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 many eggs would we need to make 9 dozen cookies? How much brown sugar would I need if I had 1 ½ cups white sugar?

17. 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

18. Chemistry Recipes You need a balanced reaction before you start! You need a balanced reaction before you start! Ex: 2 Na + Cl 2  2 NaCl Ex: 2 Na + Cl 2  2 NaCl This reaction tells us that by mixing 2 moles of Na with 1 mole of Cl 2 we will get 2 moles of NaCl This reaction tells us that by mixing 2 moles of Na with 1 mole of Cl 2 we will get 2 moles of NaCl What if we wanted 4 moles of NaCl? 10 moles? 50 moles? What if we wanted 4 moles of NaCl? 10 moles? 50 moles?

19. Practice Write the balanced rxn for hydrogen gas reacting with oxygen gas to produce water Write the balanced rxn for hydrogen gas reacting with oxygen gas to produce water 2 H 2 + O 2  2 H 2 O 2 H 2 + O 2  2 H 2 O Moles of reactants are needed? Moles of reactants are needed? What if we wanted 4 moles of water? What if we wanted 4 moles of water? If we had 3 moles of O 2, how much H 2 would we need? How much water would we get? If we had 3 moles of O 2, how much H 2 would we need? How much water would we get? If we had 50 moles of hydrogen, how much oxygen would we need? How much water produced? If we had 50 moles of hydrogen, how much oxygen would we need? How much water produced? 2 mol H 2 1 mol O 2 4 mol H 2 2 mol O 2 6 mol H 2, 6 mol H 2 O 25 mol O 2, 50 mol H 2 O

20. Mole Ratios Mole ratios can be used to calculate the moles of one chemical from the given amount of a different chemical Mole ratios can be used to calculate the moles of one chemical from the given amount of a different chemical Ex: How many moles of Cl 2 are needed to react with 5 moles of Na (using all the Na)? Ex: How many moles of Cl 2 are needed to react with 5 moles of Na (using all the Na)? 2 Na + Cl 2  2 NaCl 5 moles Na 1 mol Cl 2 2 mol Na = 2.5 moles Cl 2

21. Mole-Mole Conversions How many moles of NaCl will be produced if you react 2.6 moles of Cl 2 with an excess of Na? How many moles of NaCl will be produced if you react 2.6 moles of Cl 2 with an excess of Na? 2 Na + Cl 2  2 NaCl 2.6 moles Cl 2 2 mol NaCl 1 mol Cl 2 = 5.2 moles NaCl

22. Mole-Mass Conversions Amounts of a chemical are often given in grams instead of moles Amounts of a chemical are often given in grams instead of moles We still go through moles and use the mole ratio, but now we also use molar mass to get to grams We still go through moles and use the mole ratio, but now we also use molar mass to get to grams Ex: How many grams of Cl 2 are required to react completely with 5.00 moles of Na to produce NaCl? Ex: How many grams of Cl 2 are required to react completely with 5.00 moles of Na to produce NaCl? 2 Na + Cl 2  2 NaCl 5.00 moles Na 1 mol Cl 2 70.90g Cl 2 2 mol Na 1 mol Cl 2 = 177g Cl 2

23. You Practice Calculate the mass in grams of iodine required to react completely with 0.50 moles of Al. Calculate the mass in grams of iodine required to react completely with 0.50 moles of Al. 2 Al + 3 I 2  2 AlI 3

24. Mass-Mole We can also start with mass and convert to moles of product or another reactant We can also start with mass and convert to moles of product or another reactant We use molar mass and the mole ratio to get to moles of the compound of interest We use molar mass and the mole ratio to get to moles of the compound of interest Calculate the number of moles of ethane (C 2 H 6 ) needed to produce 10.0 g of water Calculate the number of moles of ethane (C 2 H 6 ) needed to produce 10.0 g of water 2 C 2 H 6 + 7 O 2  4 CO 2 + 6 H 2 0 2 C 2 H 6 + 7 O 2  4 CO 2 + 6 H 2 0 10.0 g H 2 O 1 mol H 2 O 2 mol C 2 H 6 18.0 g H 2 O 6 mol H 2 0 = 0.185 mol C 2 H 6

25. Mass-Mass Conversions Most often we are given a starting mass and want to find out the mass of a product (called theoretical yield) or how much of another reactant we need to completely react with it (no leftovers!) Most often we are given a starting mass and want to find out the mass of a product (called theoretical yield) or how much of another reactant we need to completely react with it (no leftovers!)

26. Steps for Mass to Mass 1. Grams to moles of given substance 2. Mole ratio 3. Moles to grams of compound

27. Mass-Mass Conversion Ex. Calculate how many grams of ammonia are produced when you react 2.00g of nitrogen with excess hydrogen. Ex. Calculate how many grams of ammonia are produced when you react 2.00g of nitrogen with excess hydrogen. N 2 + 3 H 2  2 NH 3 N 2 + 3 H 2  2 NH 3 2.00g N 2 1 mol N 2 2 mol NH 3 17.06g NH 3 28.02g N 2 1 mol N 2 1 mol NH 3 = 2.4 g NH 3

28. Read pg 110-114 Read pg 110-114 Do: #4-7 pg 115 #9 & 10 pg 117 #9 & 10 pg 117 19 & 20 pg 125 19 & 20 pg 125 #Check your answers on pg 151

29. Practice How many grams of calcium nitride are produced when 2.00 g of calcium reacts with an excess of nitrogen? How many grams of calcium nitride are produced when 2.00 g of calcium reacts with an excess of nitrogen?

30. Practice Given the equation C + O 2  CO Given the equation C + O 2  CO (a) Balance the equation (b) How many moles of O 2 are required to react with 2.36 moles of C? (c) How many moles of CO will be formed from 5.9 moles of C reacting?