1. The recipe of chemistry Stoichiometry Ch 9

2. 2 Analogy Suppose you are preparing a cake. Each Cake (Ck) requires 1.0 cake mix (Cm), 0.5 cup of oil (Oi), 1.0 cup of water (Wa) and 2.0 eggs (Eg). 1. Write the balanced equation for making cake: 1 ______ + 0.5 ______ + 1______ +2 _______  1 _______ 1.0 cake mix + 0.5 cups oil + 1.0 cup water + 2 eggs  1.0 cake 2. If you have 2 cake mixes, 2 cups oil, 3 cups water, 4 eggs, how many cakes can you make, what and how much is left over? Warm up

3. Calculating Cakes Calculate the number of cakes (Ck) that can be made from 12 cake mixes (Cm) – 12Cm x 1 Ck = 12 Ck 1 Cm Calculate the number of cakes (Ck) that can be made from 10.0 cups of oil (Oi) – 10.0 Oi x 1 Ck = 20 Ck 0.5Oi If you need to make 29 cakes (Ck), how many eggs (Eg) do you need? – 29 Ck x 2 Eg = 58 Eg 1 Ck 1.0 cake mix + 0.5 cups oil + 1.0 cup water + 2 eggs  1.0 cake

4. Equations are a chemist’s recipe. – Eqs tell chemists what amounts of reactants to mix and what amounts of products to expect. When you know the quantity of onesubstance in a rxn, you can calculate the quantity of any other substance consumed or created in the rxn. Stoichiometry: the calculation of quantities in chemical reactions

5. Why should you care? Nearly everything we use is manufactured from chemicals. – Soaps, shampoos, conditioners, CD’s, cosmetics, medications, clothes.  For a manufacturer to make a profit the chemical processes carried out in industry must be economical  A balanced equation is needed and used so chemicals are not wasted when making products

6. Reading Chemical Equations How would you read: – N 2 (g) + H 2 (g)  NH 3 (g) Balance and read: – N 2 (g) + 3 H 2 (g)  2 NH 3 (g) – Coefficients can represent different possible units Atoms/molecules Moles Mass in grams – Mass of reactants equals mass of products – Law of Conservation of mass Liters (if compound is a gas at STP)

7. 1 mol N 2 +3 mol N 2  2 mol NH 3 28.0 g N 2 +3 (2.0 g H 2 )  2 (17.0 g NH 3 ) 34.0 g reactants  34.0 g products +  22.4 L N 2 67.2 L H 2  44.8 L NH 3 22.4 L N2N2 +3H 2  2NH 3

9. MOLE ratios: – What are the possible mole ratios in: N 2 (g) + 3H 2 (g)  2NH 3 (g) – 1 mole of N 2 reacts with 3 moles of H 2 to produce 2 moles of NH 3. – Possible mole ratios for this formula: 1N 2 1N 2 3H 2 3H 2 2NH 3 2NH 3 Reaction to form ammonia in this 1:3:2 ratio. Mole ratios are CONVERSION FACTORS! Once you have the ratios, you can perform calcs. (a.k.a. STOICHIOMETRY)

10. Conversion of Quantities in Moles Amount of given (mol) Amount of unkown (mol) Mole unknown Mole given X = Mole ratio: from balanced equation Ex: How many moles of water are produced from 5.80 moles of oxygen gas? O 2 + H 2  H 2 O 1.Write equation 2.Balance! 3.Set up conversion factor O 2 + 2H 2  2 H 2 O 5.80mole O 2 x 2 mol H 2 O 1 mol O 2 11.6 moles water Pg 305

11. N 2 (g) + 3H 2 (g)  2NH 3 (g) 1. How many moles of ammonia are produced from 0.60 moles of N 2 ? – (1.2 mol NH 3 ) 2. How many moles of H 2 are needed to react with 0.43 moles of N 2 gas? – (1.3 mol H 2 ) 3. How many moles of H 2 are needed to produce 1.98 moles of ammonia (NH 3 )? – (2.97 mol H 2 )

12. Amount of given (mol) Amount of unkown (mol) Mole unknown Mole given X = Mole ratio: from balanced equation 5. The decomposition of potassium chlorate, KClO 3 into potassium chloride and oxygen gas is used as a source of oxygen in the lab. How many moles of potassium chlorate are needed to produce 15 mol of oxygen gas? 10 mol KClO 3 4. Ammonia, NH 3 is a widely used fertilizer and used in household cleaners. How many moles of ammonia are produced when 6 mol of H gas react with excess nitrogen gas? 4 mol NH 3 1.Write equation 2.Balance! 3.Set up conversion factor

13. Historical Chemistry: pg 303, #1-2 Ch 9.1

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15. Sn + 2HF  SnF 2 + H 2 1.How many moles of SnF 2 will be produced by 12.5 moles of HF? 1.How many moles HF are needed to produce 6.85 moles of SnF 2 ? Warm up

16. Calculating using MASS quantities No lab balance measures moles directly, instead grams is a more practical unit. To calculate grams: 1. convert to moles first, then grams – Using our same example, you can calculate how many grams of each compound: N 2 (g) + 3H 2 (g)  2NH 3 (g) REMEMBER: when you use a gram/mole conversion factor: 1 mol = molar mass 3.00 g N 2 x x x 1 mol 28g 2 mol NH 3 1 mol N 2 17 g 1 mol

18. Conversion of amount in Moles & Mass Ex 1: What mass, in grams, of glucose is produced when 3.00 mol of water reacts with excess carbon dioxide to produce glucose and oxygen? 1.Write equation 2.Balance! 3.Set up conversation factor 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 3.00mol x x 1 mol glucose 180.2g 6 mol water 1 mole 90.1g glucose Particle A Mass A Volume A Particle B Mass B Volume B Mole A Mole B 6.022x10 23 Molar Mass 22.4 L Mole Ratio

19. 2.What mass of carbon dioxide is needed to react with 3.00 mol water? 2.How many moles of H 2 O are formed from a reaction using 824g NH 3 is the reaction: NH 3 + O 2  NO + H 2 O (unbalanced) 4NH 3 + 5O 2  4NO + 6H 2 O examples 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 132g CO 2 72.5 mol H 2 O Particle A Mass A Volume A Particle B Mass B Volume B Mole A Mole B 6.022x10 23 Molar Mass 22.4 L Mole Ratio

20. Ex 4: How many grams of SnF 2 are produced from the reaction of 30.00g HF with Sn. Sn (s) + 2HF (g)  SnF 2(s) +H 2(g) 30.00g HF x x x 5. How many grams of NH 4 NO 3 are required to produce 33.0g N 2 O? (the laughing gas needed for an anesthetic in dentistry) NH 4 NO 3(s)  N 2 O (g) + 2H 2 O (l) Conversion of amount: Mass to Mass Particle A Mass A Volume A Particle B Mass B Volume B Mole A Mole B 6.022x10 23 Molar Mass 22.4 L Mole Ratio 1 mol HF 20.0 g HF 1 mol SnF 2 2 mol HF 156.7g SnF 2 1 mol SnF 2 117.5g SnF 2 60.0g NH 4 NO 3 6. How many molecules of oxygen gas are produced when 29.2 g of water is decomposed? (4.88 * 10 23 molecules of O 2 )

21. More Problems to Practice 1.Carbon dioxide is produced from the synthesis of oxygen gas with carbon monoxide. Write and balance this chemical equation and then tell how many liters of oxygen gas are required to burn 3.86 liters of carbon monoxide. Assume STP. – (1.93 L O 2 ) 2. How many grams of NH 4 NO 3 are required to produce 33.0g N 2 O? (the laughing gas needed for an anesthetic in dentistry) NH 4 NO 3(s)  N 2 O (g) + 2H 2 O (l) 3. How much water in grams is produced in this reaction? 60.0g NH 4 NO 3 27.0g H 2 O

22. Stoichiometry Practice Answer in classwork section of notebook: N 2 (g) + 3H 2 (g)  2NH 3 (g) 1.Calculate the number of grams of ammonia produced by the reaction of 5.40 g of H 2 with N 2. (30.6 g NH 3 ) 2.Calculate the number of liters of N 2 needed in order to react with 0.78 moles of H 2. (5.8 L N 2 ) 3.Calculate the grams of N 2 needed in order to produce 9.23 x 10 23 molecules of NH 3. (21.5 g N 2 ) Particle A Mass A Volume A Particle B Mass B Volume B Mole A Mole B 6.022x10 23 Molar Mass 22.4 L Mole Ratio

23. Stoichiometry Practice Answer in classwork section of notebook: N 2 (g) + 3H 2 (g)  2NH 3 (g) 1.Calculate the number of grams of ammonia produced by the reaction of 5.40 g of H 2 with N 2. (30.6 g NH 3 ) 2.Calculate the number of liters of N 2 needed in order to react with 0.78 moles of H 2. (5.82 L N 2 ) 3.Calculate the grams of N 2 needed in order to produce 9.23 x 10 23 molecules of NH 3. – (21.5 g N 2 ) Ch 9.2: Answer #2-4 on page 311

24. MOLE-MOLE RATIO You will ALWAYS use the new MOLE-MOLE ratio step to get you from where you are to where you are are going. Particle A Mass A Volume A Particle B Mass B Volume B Mole A Mole B 6.022x10 23 Molar Mass 22.4 L Mole Ratio

25. More Problems to Practice Carbon dioxide is produced from the synthesis of oxygen gas with carbon monoxide. Write and balance this chemical equation and then tell how many liters of oxygen gas are required to burn 3.86 liters of carbon monoxide. Assume STP. – (1.93 L O 2 )

26. Problems to Practice Aluminum reacts with oxygen to produce Aluminum Oxide. How many moles of aluminum are needed to form 3.7 moles of Aluminum Oxide? Write the balanced equation and solve. –(7.4 mol Al)

27. More Problems to Practice How many molecules of oxygen gas are produced when 29.2 g of water is decomposed? The balanced chemical equation is given for you. Use your new mole map to solve. 2H 2 O –electricity  2H 2 + O 2 – (4.88 * 10 23 molecules of O 2 ) How many molecules of oxygen are produced by the decomposition of 6.54 g of Potassium Chlorate? The balanced chemical equation is given for you. Use your new mole map to solve. 2KClO 3  2KCl + 3O 2 – (4.82 * 10 22 molecules of O 2 )

28. Even More Problems Sodium hydroxide reacts with Sulfuric acid to produce water and Sodium Sulfate. Calculate the amount of water (in grams) that would be produced from 40.87 g of the acid. – (15.0 g H 2 O) In a combustion reaction, C 2 H 4 reacts with oxygen to produce H 2 O and CO 2 in the following reaction. Balance it and then determine the amount of oxygen (in grams) that is consumed if 2.69g of water is produced. – _____C 2 H 4 + _____O 2  _____CO 2 + _____H 2 O (7.17 g O 2 )

29. Mole to mass Amount of given (mol) Mole unknown molar mass unknown(g) Mole given1 mole unkown Mole ratio: (balanced equation) mass of unkown (g) X x = Molar mas: (periodic table) Mass of given (g) 1 mole given mol unknown molar mass mol given given (g) Mole ratio: (balanced equation) Amount unkown (mol) X x = Molar mas: (periodic table)

30. mass of unknown (g) Mass of given (g) X x X = 1 mole given mol unknown mole mass molar mass mol given 1 mol given (g) unknown

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32. Warm up 1.Carbon dioxide is produced from the synthesis of oxygen gas with carbon monoxide. Write and balance this chemical equation and then tell how many liters of oxygen gas are required to burn 3.86 liters of carbon monoxide. Assume STP. – (1.93 L O 2 ) Particle A Mass A Volume A Particle B Mass B Volume B Mole A Mole B 6.022x10 23 Molar Mass 22.4 L Mole Ratio

33. The difference in the optimal, expected outcome and the actual tested outcome Theoretical yield vs Actual yield: Ch 9.3 Experimentation is not perfect Not all reactant are react so some may be left over Conditions may not be perfect for a full reaction

35. How many sandwiches, how much excess?

36. Limiting Reagent Limiting reagent : reactant that determines the amount of product that can be produced. – It limited… Excess reagent: reactant that is not used up in the reaction - there is more available than needed Steps to determine LR Calculate theoretical yield (g or mol) Determine limited reagent Use the original actual yield of the limiting reactant to calculate product produced (in moles or grams)

37. Flask123456 Volume acetic acid (mL) 25ml Sodium bicarbona te (g) 0.50g1.00g1.50g2.00g2.50g3.00g Demo Which system will produce the most CO 2 product?

38. Problems to Practice Ex 1. Given the following balanced equation, determine which is the LR if 2.70 moles of C 2 H 4 is reacted with 6.30 moles of O 2. C 2 H 4 + 3 O 2  2 H 2 O + 2 CO 2 – (O 2 is LR) 2. Using the info gathered from above, calculate the GRAMS of water that will be produced. 75.6 g H 2 O 2.70 mol C 2 H 4 x = 5.4 mol H 2 O 2 mole H 2 O 1 mole C 2 H 4 6.30 mol O 2 x = 4.20 mol H 2 O 2 mole H 2 O 3 mole O 2 Less= limiting reagent=O 2 4.20mol x 18g/mol =

39. More Problems to Practice 3. Identify the LR when 6.00 g HCl reacts with 5.00 g Mg in the following reaction: Mg + 2HCl  MgCl 2 + H 2 – (HCl is LR) 4. Using the info gathered from above, calculate the GRAMS of hydrogen gas that will be produced. – (0.164 g H 2 )

40. Percent Yield % yield = ____actual yield___ x 100 theoretical yield measure of the efficiency of a reaction carried out in lab. Actual yield would be given in problem or determined from actually performing the lab. Theoretical yield can be calculated using the Limiting Reagent.

41. Percent Yield: Problem to Practice If 15.0 g of nitrogen gas reacts with 15.0 g of hydrogen gas, 10.5 g of ammonia (NH 3 ) is produced. Calculate the percent yield. – N 2 yields 1.07 mol NH 2 – H 2 yields 5.0mol NH 2 – Limiting reactant: N 2 – (theoretical yield: 18.2 g NH 3 ) – (percent yield: 57.7%) % yield = ____actual yield___ x 100 theoretical yield 1.Balance chemical equation 2.Find limiting reactant 3.Calculate theoretical yield 4.Find percent yield

42. 1.Calculate the theoretical yield of hydrogen gas. 1.23g H 2 2.Calculate the percent yield if 1.15 grams of H 2 are produced. 93.5% Then continue the limiting reactant worksheet: *fixed part B #3:.900 grams CO 2 * use page 314 to 315 to help * “continuation questions” are optional! 15.0 g Mg in the following reaction: Mg + 2HCl  MgCl 2 + H 2 Warm up

43. Classwork Pg 325 “Standardized Test Prep” #1-12

44. Particle A Mass A Volume A Particle B Mass B Volume B Mole A Mole B 6.022x10 23 Molar Mass 22.4 L Mole Ratio

45. I’m not sure I’ve got this….

47. HS-PS1-7.Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction. HS-PS1-6.Refine the design of a chemical system by specifying a change in conditions that would produce increased amounts of products at equilibrium. HS-PS1-5.Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs. HS-PS1-3.Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles. Common Core Standards

48. HS-PS1-7.Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction. CA State Standards D2. Investigate quantitative relationships in chemical reactions, and solve related problems; D3. Demonstrate an understanding of the mole concept and its significance to the quantitative analysis of chemical reactions. Common Core Standards

49. HS-PS1-6.Refine the design of a chemical system by specifying a change in conditions that would produce increased amounts of products at equilibrium. Common Core Standards

50. HS-PS1-5.Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs. Common Core Standards

51. HS-PS1-3.Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles. Common Core Standards