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Stoichiometry. Baking 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.
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Baking 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?
Chemistry Recipes • chemists have recipes as well, but we call them reaction equations • we use moles to measure • we use chemical compounds as our ingredients
Chemistry Recipes • 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! • Example: 2 Na + Cl2 2 NaCl • This reaction tells us that by mixing 2 moles of sodium with 1 mole of chlorine we will get 2 moles of sodium chloride
Guided Notes • Stoichiometry • study of the quantity relationships in a chemical reaction • based on balancedchemical equations • The coefficients in a balancedequation give the moleratio for the substance involved in the reaction.
Mole to Mole Conversions: • When elemental aluminum reacts with elemental iodine, aluminum iodide is produced. 2Al + 3I2 2AlI3 mole ratios: 2 mol Al = 3mol I22 mol Al = 2 mol AlI3 3 mol I2 = 2 mol AlI3 If you start with 4 moles of Al, how many moles of AlI3 will be produced? 4 moles Al 2 mol AlI3 2 mol Al = 4 moles AlI3
2. Dinitrogen tetrahydride reacts with Dinitrogen tetroxide to produce nitrogen gas and water. 2N2H4(g) + 1N2O4(g)3N2(g) + 4H2O(g) a. How many moles N2O4 is needed to react with 2.72 moles N2H4? 2N2H4(g) + 1N2O4(g)3N2(g) + 4H2O(g) ? mol Units match 2.72 mol 2.72 mol N2H4 = moles N2O4 1.36 b. How many moles of N2 is produced from 2.72 moles N2H4? 2N2H4(g) + 1N2O4(g) 3N2(g) + 4H2O(g) 2.72 mol ? mol 2.72 mol N2H4 = mole N2 4.08
Calculations molar mass Avogadro’s numberGrams Moles particles Everything must go through Moles!!!
Mass to Mole Conversions: • 1. How many moles of water will be produced when 8.0 grams of hydrogen gas react with the oxygen in the air? • (Hint: To “make the switch” between different substances in a reaction, use the mole ratio from the balanced equation.) • 2 H2 + O2 2 H2O 8.0 g H2 1 mol H2 2 mol H2O 2.0 g H2 2 mol H2 = 4.0 mol H2O
Mass to Mole Conversions: 2. In photosynthesis, carbon dioxide and water react to form glucose, C6H12O6 and oxygen gas. 6 CO2 + 6 H2O C6H12O6 + 6 O2 • If 15.6 grams of carbon dioxide react, how many moles of glucose will be produced 15.6 g CO2 1 mol CO2 1 mol C6H12O6 1 44.0 g CO2 6 mol CO2 = 0.0591 mol C6H12O6
Mass to Mole Conversions: 2. In photosynthesis, carbon dioxide and water react to form glucose, C6H12O6 and oxygen gas. 6 CO2 + 6 H2O C6H12O6 + 6 O2 • How many grams of carbon dioxide must react to produce 0.25 moles of glucose? 0.25mol C6H12O6 6 mol CO2 44.0g CO2 1 1 molC6H12O6 1 mol CO2 = 66 g CO2