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Stoichiometry Notes New Section in Table of Contents.

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Presentation on theme: "Stoichiometry Notes New Section in Table of Contents."— Presentation transcript:

1 Stoichiometry Notes New Section in Table of Contents

2 Real Life Application Ingredients  2 1/4 cups all-purpose flour  1 teaspoon baking soda  1 teaspoon salt  1 cup (2 sticks) butter, softened  3/4 cup granulated sugar  3/4 cup packed brown sugar  1 teaspoon vanilla extract  2 large eggs  2 cups (12-oz. pkg.) NESTLÉ® TOLL HOUSE® Semi-Sweet Chocolate Morsels  1 cup chopped nuts Ingredients  2 1/4 cups all-purpose flour  1 teaspoon baking soda  1 teaspoon salt  1 cup (2 sticks) butter, softened  3/4 cup granulated sugar  3/4 cup packed brown sugar  1 teaspoon vanilla extract  2 large eggs  2 cups (12-oz. pkg.) NESTLÉ® TOLL HOUSE® Semi-Sweet Chocolate Morsels  1 cup chopped nuts

3 Real Life Application  We cannot forget about the law of conservation of mass.  The mass of what we put in must be equal to what we get out.  KC 1: The excess reactants are all the leftover unused reactants. (The reactant that’s leftover).  We cannot forget about the law of conservation of mass.  The mass of what we put in must be equal to what we get out.  KC 1: The excess reactants are all the leftover unused reactants. (The reactant that’s leftover).

4 Particle and Mole Relationships  Chemical reactions stop when one of the reactants is used up  KC 2: Stoichiometry is the study of quantitative relationships between the amounts of reactants used and amounts of products formed by a chemical reaction  So based on how much reactant you put in you can calculate how much product you will get out  Chemical reactions stop when one of the reactants is used up  KC 2: Stoichiometry is the study of quantitative relationships between the amounts of reactants used and amounts of products formed by a chemical reaction  So based on how much reactant you put in you can calculate how much product you will get out

5 Particle and Mole Relationships

6  KC 3: A mole ratio is a ratio between the numbers of moles of any 2 substances in a balanced equation  This can only be determined from a balanced chemical equation  KC 3: A mole ratio is a ratio between the numbers of moles of any 2 substances in a balanced equation  This can only be determined from a balanced chemical equation

7 Particle and Mole Relationships  Let practice: What is the mole-to-mole ratio for…  10C 2 H 4 O + 15O 2  20CO 2 + 2H 2 O  CH 4 + 2O 2  CO 2 + 2H 2 O  H 2 + O 2  H 2 O  Let practice: What is the mole-to-mole ratio for…  10C 2 H 4 O + 15O 2  20CO 2 + 2H 2 O  CH 4 + 2O 2  CO 2 + 2H 2 O  H 2 + O 2  H 2 O

8 Using Stoichiometry CH 4 + 2O 2  CO 2 + 2H 2 O Mol CH 4 Mole H 2 O

9 Using Stoichiometry Key Concept 4: How many moles of SO 3 are formed if you start with 5 moles of Sulfur and have excess Oxygen? ____S + ____O 2  ____SO 3 Key Concept 4: How many moles of SO 3 are formed if you start with 5 moles of Sulfur and have excess Oxygen? ____S + ____O 2  ____SO 3

10 Using Stoichiometry 4Fe(s) + 3O 2 (g)  2Fe 2 O 3 (s) 12.37g Fe Mol Fe Mole Fe 2 O 3 ?? g Fe 2 O 3

11 Using Stoichiometry  How many grams of Fe 2 O 3 are formed when 12.37g of iron reacts with excess oxygen using the balanced chemical equation below: 4Fe(s) + 3O 2 (g)  2Fe 2 O 3 (s)  How many grams of Fe 2 O 3 are formed when 12.37g of iron reacts with excess oxygen using the balanced chemical equation below: 4Fe(s) + 3O 2 (g)  2Fe 2 O 3 (s)

12 Using Stoichiometry Key Concept 5: How many grams of lithium nitrate will be needed to make 250 grams of lithium sulfate, assuming that you have an adequate amount of lead (IV) sulfate to do the reaction? ____Pb(SO 4 ) 2 + ____LiNO 3  ____Pb(NO 3 ) 4 + ____Li 2 SO 4 Key Concept 5: How many grams of lithium nitrate will be needed to make 250 grams of lithium sulfate, assuming that you have an adequate amount of lead (IV) sulfate to do the reaction? ____Pb(SO 4 ) 2 + ____LiNO 3  ____Pb(NO 3 ) 4 + ____Li 2 SO 4

13 Using Stoichiometry Key Concept 6: How many grams of sodium sulfate will be formed if you start with 200 grams of sodium hydroxide and you have an excess of sulfuric acid? ____NaOH + ____H 2 SO 4  ____H 2 O + ____Na 2 SO 4 Key Concept 6: How many grams of sodium sulfate will be formed if you start with 200 grams of sodium hydroxide and you have an excess of sulfuric acid? ____NaOH + ____H 2 SO 4  ____H 2 O + ____Na 2 SO 4

14 Using Stoichiometry  New Conversion Factor: 1 mol of gas = 22.4L (at STP = standard temperature and pressure)  How many moles of sodium chloride are in 3.87 L?  How many grams of sodium chloride are in 3.87L?  New Conversion Factor: 1 mol of gas = 22.4L (at STP = standard temperature and pressure)  How many moles of sodium chloride are in 3.87 L?  How many grams of sodium chloride are in 3.87L?

15 Using Stoichiometry 4Fe(s) + 3O 2 (g)  2Fe 2 O 3 (s) 12.37g Fe Mol Fe Mole Fe 2 O 3 L Fe 2 O 3

16 Using Stoichiometry Key Concept 7: How many liters of sodium sulfate will be formed if you start with 200 grams of sodium hydroxide and you have an excess of sulfuric acid? ____NaOH + ____H 2 SO 4  ____H 2 O + ____Na 2 SO 4 Key Concept 7: How many liters of sodium sulfate will be formed if you start with 200 grams of sodium hydroxide and you have an excess of sulfuric acid? ____NaOH + ____H 2 SO 4  ____H 2 O + ____Na 2 SO 4

17 Practice  How many grams of water are formed when.25L of propane (C 3 H 8 ) burns at STP with excess oxygen according to the reaction below: _____C 3 H 8 + ______O 2 → ______CO 2 + _______H 2 O  How many grams of water are formed when.25L of propane (C 3 H 8 ) burns at STP with excess oxygen according to the reaction below: _____C 3 H 8 + ______O 2 → ______CO 2 + _______H 2 O

18 Practice  How many grams of CaCl 2 are formed when 21.3g of Ca(OH) 2 reacts with excess HCl? _____Ca(OH) 2 + _____HCl  ______CaCl 2 + ______H 2 O  How many grams of CaCl 2 are formed when 21.3g of Ca(OH) 2 reacts with excess HCl? _____Ca(OH) 2 + _____HCl  ______CaCl 2 + ______H 2 O

19 Practice  How many grams of BaCl 2 are formed from moles of Ba(ClO 3 ) 2 ? _______Ba(ClO 3 ) 2 → _______BaCl 2 + _____O 2  How many grams of BaCl 2 are formed from moles of Ba(ClO 3 ) 2 ? _______Ba(ClO 3 ) 2 → _______BaCl 2 + _____O 2

20 Practice  Iron(III) oxide, Fe 2 O 3, can be reduced to iron by passing carbon monoxide, CO, over the heated oxide. How many moles of iron can be produced from moles of iron (III) oxide and excess carbon monoxide? ______Fe 2 O 3(s) + _____CO (g)  _____Fe (s) ­ + _____CO 2(g)  Iron(III) oxide, Fe 2 O 3, can be reduced to iron by passing carbon monoxide, CO, over the heated oxide. How many moles of iron can be produced from moles of iron (III) oxide and excess carbon monoxide? ______Fe 2 O 3(s) + _____CO (g)  _____Fe (s) ­ + _____CO 2(g)

21 Practice  Butyne, C 4 H 6, burns in the presence of oxygen in air to produce carbon dioxide, CO 2, and water H 2 O. How many moles of oxygen will be required to produce moles of carbon dioxide? ______C 4 H 6 + ______O 2  ______CO 2 + ______H 2 O  Butyne, C 4 H 6, burns in the presence of oxygen in air to produce carbon dioxide, CO 2, and water H 2 O. How many moles of oxygen will be required to produce moles of carbon dioxide? ______C 4 H 6 + ______O 2  ______CO 2 + ______H 2 O

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23 Limiting and Excess Reactants  KC 8: If you have 2 givens in your problem, it is a limiting reactant problem  KC 9: The reactant that produces the smallest amount of a product is the limiting reactant. This is the reactant that will be used up first in the reaction.  KC 8: If you have 2 givens in your problem, it is a limiting reactant problem  KC 9: The reactant that produces the smallest amount of a product is the limiting reactant. This is the reactant that will be used up first in the reaction.

24 Example  How many grams of Cu can be formed when g of Fe reacts with g of CuCl 2 ? 2 Fe + 3 CuCl 2  3 Cu + 2FeCl 3  How many grams of Cu can be formed when g of Fe reacts with g of CuCl 2 ? 2 Fe + 3 CuCl 2  3 Cu + 2FeCl 3

25 Steps for solving LR problems  KC 10: 1.Write down the givens 2.Use molar mass to convert to moles 3.Use mole ratio from the balanced equation 4.Convert to desired unit 5.The correct answer is the smallest answer as the reaction will stop once one reactant is gone  KC 10: 1.Write down the givens 2.Use molar mass to convert to moles 3.Use mole ratio from the balanced equation 4.Convert to desired unit 5.The correct answer is the smallest answer as the reaction will stop once one reactant is gone

26 Limiting and Excess Reactant  KC 11: 80.0g Cu reacts with 25.0g S. Determine which is the limiting reactant and calculate how much Cu 2 S is formed in grams? 2Cu(s) + S(s) → Cu 2 S(s)  KC 11: 80.0g Cu reacts with 25.0g S. Determine which is the limiting reactant and calculate how much Cu 2 S is formed in grams? 2Cu(s) + S(s) → Cu 2 S(s)

27 Limiting and Excess Reactant  KC 12: What is the limiting reactant if 65g of each reactant is present? ___Zn + ___HCl → ___ZnCl 2 + ___H 2  KC 12: What is the limiting reactant if 65g of each reactant is present? ___Zn + ___HCl → ___ZnCl 2 + ___H 2

28 Excess and Percent Yield  KC 13: To find how much excess you have you must take the limiting reactant and solve for the excess reactant. You need to look at what you are given versus what you need.

29 Excess Reactant - Example  How many grams of Cu can be formed when g of Fe reacts with g of CuCl 2 ? 2 Fe + 3 CuCl 2  3 Cu + 2FeCl 3 CuCl 2 – limiting reactant 188.5g Cu is formed  How many grams of excess is left over?  How many grams of Cu can be formed when g of Fe reacts with g of CuCl 2 ? 2 Fe + 3 CuCl 2  3 Cu + 2FeCl 3 CuCl 2 – limiting reactant 188.5g Cu is formed  How many grams of excess is left over?

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31 Percent Yield  KC 14: % yield = actual yieldx 100 theoretical yield  KC 15: Actual yield must be found experimentally. It is recognized by words like “produced” and “formed”  KC 16: Theoretical yield is done using stoichiometry. It is a prediction and will always be done using math.  KC 14: % yield = actual yieldx 100 theoretical yield  KC 15: Actual yield must be found experimentally. It is recognized by words like “produced” and “formed”  KC 16: Theoretical yield is done using stoichiometry. It is a prediction and will always be done using math.

32 Percent Yield  KC 17: A student calculated she should obtain 28g of a substance. In the experiment, 25g was produced. What is the percent yield of the experiment?

33 Percent Yield - Example  g of Fe reacts with g of CuCl 2 to form 170.3g of copper. What is the percent yield of copper? 2 Fe + 3 CuCl 2  3 Cu + 2FeCl 3  g of Fe reacts with g of CuCl 2 to form 170.3g of copper. What is the percent yield of copper? 2 Fe + 3 CuCl 2  3 Cu + 2FeCl 3

34 Practice  KC 18: 11.2g of nickel (II) sulfide reacts with 5.43g of oxygen producing 4.97g of nickel (II) oxide. What is the percent yield of this reaction? _____NiS 2 + _____O 2 → _____NiO + _____SO 2  KC 18: 11.2g of nickel (II) sulfide reacts with 5.43g of oxygen producing 4.97g of nickel (II) oxide. What is the percent yield of this reaction? _____NiS 2 + _____O 2 → _____NiO + _____SO 2

35 Practice  KC 19: You are given 0.45g of Al(OH) 3 and 0.55g of H 2 SO 4. The reaction produces 0.15g of water. What is the percent yield of this reaction? ____Al(OH) 3 + _____H 2 SO 4 → _____Al 2 (SO 4 ) 3 + _____H 2 O  KC 19: You are given 0.45g of Al(OH) 3 and 0.55g of H 2 SO 4. The reaction produces 0.15g of water. What is the percent yield of this reaction? ____Al(OH) 3 + _____H 2 SO 4 → _____Al 2 (SO 4 ) 3 + _____H 2 O

36 Practice  KC 20: You are given 3 moles of lithium and 3 moles of nitrogen. The reaction produces.5 moles of lithium nitride. What is the percent yield of this reaction? ____Li + _____N 2 → _____Li 3 N  KC 20: You are given 3 moles of lithium and 3 moles of nitrogen. The reaction produces.5 moles of lithium nitride. What is the percent yield of this reaction? ____Li + _____N 2 → _____Li 3 N


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