Stoichiometry Unit 6 Mrs. Mansberger

Chemical Stoichiometry Stoichiometry - The study of quantities of materials consumed and produced in chemical reactions. Stoichiometry - The study of quantities of materials consumed and produced in chemical reactions.

Best Ever Chewy Chocolate Chunk Cookies INGREDIENTS: 1/2 cup butter, softened 1/3 cup chocolate syrup 1 cup packed brown sugar 1/2 cup white sugar 2 eggs 2 tablespoons corn syrup 2 teaspoons vanilla extract 2 1/2 cups all-purpose flour 1 teaspoon baking soda 1/2 teaspoon salt 1 (11.5 ounce) package semi-sweet chocolate chunks Recipe makes 3 dozen cookies. DIRECTIONS: Preheat the oven to 375 degrees F (190 degrees C). In a medium bowl, cream together the butter, chocolate syrup, brown sugar and white sugar until smooth. Beat in the eggs, one at a time, then stir in the corn syrup and vanilla. Combine the flour, baking soda and salt; stir into the creamed mixture until just blended. Mix in the chocolate chunks by hand. Drop cookies by 1/4 cupfuls onto ungreased cookie sheets. Bake for 12 to 14 minutes in the preheated oven. Allow cookies to cool on baking sheet for 5 minutes before removing to a wire rack to cool completely.

What would happen if I wanted to make six dozen cookies, and the recipe only called to make three dozen cookies? What would I have to do?

C 2 H 2 CaC 2 + 2H 2 O → C 2 H 2 + Ca(OH) 2 Coefficients: Representations: 1 Mole CaC 2 2 Moles H 2 O 1 Mole C 2 H 2 1 Mole Ca(OH) 2 1 mole of CaC 2 reacts with 2 moles of H 2 O to produce 1 moles of C 2 H 2 and 1 mole of Ca(OH) 2

Mole ratio: C 2 H 2 CaC 2 + 2H 2 O → C 2 H 2 + Ca(OH) 2

Complete list of mole ratios: CaC 2 → H2O→H2O→ C2H2→C2H2→ Ca(OH) 2 →

Use the chart given in your aid packet to help you with your mole conversions! This is similar to the road map you used before! MOLE STEP 6.02 X L Molar mass

Working a Stoichiometry Problem 4 KO 2  2 K 2 O 4 K + O 2  2 K 2 O mol O 2 1 A) How many moles of O 2 are needed to make 7.6 g of K 2 O? LOOK ON THE MAP TO FIGURE OUT HOW MANY STEPS! = 7.6 g K 2 O ? mol O 2 1 mol 94.2 g 2 mol 1 mol K2OK2OK2OK2O K2OK2OK2OK2O K2OK2OK2OK2O O2O2O2O2

Try this… 4 KO 2  2 K 2 O 4 K + O 2  2 K 2 O mol K D) How many moles of K are needed to make 18.0 g of K 2 O? LOOK ON THE MAP TO FIGURE OUT HOW MANY STEPS! = 18.0 g K 2 O ? mol K 1 mol 94.2 g 2 mol 4 mol K2OK2OK2OK2O K2OK2OK2OK2O K2OK2OK2OK2O K

Working a Stoichiometry Problem 4 K + O 2  2 K 2 O = 0.56 mol K ? mol O 2 1 mol O 2 4 mol K 0.14 mol O 2 C) How many moles of O 2 are needed to react with 0.56 moles of K to produce potassium oxide? LOOK ON THE MAP TO FIGURE OUT HOW MANY STEPS! 1

Try this… 4 K + O 2  2 K 2 O = 1.26 mol K ? mol K 2 O 2 mol K 2 O 4 mol K mol K 2 O B) How many moles of K 2 O are produced when 1.26 moles of K to is reacted with excess oxygen? LOOK ON THE MAP TO FIGURE OUT HOW MANY STEPS!

Questions???

Working a Stoichiometry Problem 4 K + 1 O 2  2 K 2 O 0.60 g K 2 O E) How many grams of K 2 O will be produced from 0.50 g of K? LOOK ON THE MAP TO FIGURE OUT HOW MANY STEPS! = 0.50 g K ? g K 2 O 1 mol 39.1 g 4 mol 2 mol 1 mol 94.2 g K K K K2OK2O K2OK2O K2OK2O K2OK2O K2OK2O K2OK2OK2OK2O K2OK2OK2OK2O K2OK2OK2OK2O

Try this with your partner… 4 K + 1 O 2  2 K 2 O 0.34 L O 2 F) How many liters of O 2 are needed to react with 2.4 grams of K? LOOK ON THE MAP TO FIGURE OUT HOW MANY STEPS! = 2.4 g K ? L O 2 1 mol K 39.1 g K 4 mol K 1 mol O L O 2

Questions???

CaC 2 + 2H 2 O → C 2 H 2 + Ca(OH) 2 Representations: 1 Molecule CaC 2 2 Molecules Water 1 Molecule C 2 H 2 1 Molecule Ca(OH) 2

CaC 2 + 2H 2 O → C 2 H 2 + Ca(OH) 2 Representations: 22.4 Liter CaC Liters Water 22.4 Liter C 2 H Liter Ca(OH) 2

How much water would I need if I started with 2 moles of CaC 2 ? –Remember the coefficients: 1,2,1,1 –Remember empirical formulas…. –The same ratio present in the basic equation is maintained all the time, no matter the multiplier of any coefficient. Answer: 4 CaC 2 + 2H 2 O → C 2 H 2 + Ca(OH) 2

What if I wanted to make 2 moles of Ca(OH) 2 instead of just one? (Remember the cookies) How many moles of CaC 2 would I need? 2 How many moles of H 2 O would I need? 4 CaC 2 + 2H 2 O → C 2 H 2 + Ca(OH) 2