1. CHAPTER 11 Stoichiometry 11.1 Analyzing a Chemical Reaction

2. 2 Chemical equations tell stories… 2CO(g) + O 2 (g) → 2CO 2 (g)

3. 3 11.1 Analyzing a Chemical Reaction Chemical equations tell stories… … and stories can be put into different categories Synthesis / Decomposition Single / Double replacement Precipitate reaction Polymerization reaction 2CO(g) + O 2 (g) → 2CO 2 (g)

4. 4 11.1 Analyzing a Chemical Reaction Chemical equations tell stories… But what exactly do they tell us? 2CO(g) + O 2 (g) 2CO 2 (g) They tell uswhat compounds we start with: Carbon monoxide (CO) gas Oxygen (O 2 ) gas what compounds are formed: Carbon dioxide (CO 2 ) gas

5. 5 11.1 Analyzing a Chemical Reaction Chemical equations tell stories… What else do they tell us? 2CO(g) + O 2 (g) 2CO 2 (g)

6. 6 11.1 Analyzing a Chemical Reaction Chemical equations tell stories… What else do they tell us? 2CO(g) + O 2 (g) 2CO 2 (g) 2 CO molecules2 CO 2 molecules1 O 2 molecules They tell us how much of each compound is involved

7. 7 11.1 Analyzing a Chemical Reaction Chemical equations tell stories… What else do they tell us? 2CO(g) + O 2 (g) 2CO 2 (g) stoichiometry: the study of the amounts of substances involved in a chemical reaction. 2 CO molecules2 CO 2 molecules1 O 2 molecules They tell us how much of each compound is involved

8. 8 11.1 Analyzing a Chemical Reaction 2CO(g) + O 2 (g) 2CO 2 (g) 2 CO molecules 2 dozen CO molecules 1 O 2 molecules 1 dozen O 2 molecules 2 CO 2 molecules 2 dozen CO 2 molecules

9. 9 11.1 Analyzing a Chemical Reaction 2CO(g) + O 2 (g) 2CO 2 (g) 2 CO molecules 2 dozen CO molecules 2 moles CO molecules 1 O 2 molecules 1 dozen O 2 molecules 1 mole O 2 molecules 2 CO 2 molecules 2 dozen CO 2 molecules 2 moles CO 2 molecules

10. 10 11.1 Analyzing a Chemical Reaction 2CO(g) + O 2 (g) 2CO 2 (g) 2 CO molecules 2 dozen CO molecules 2 moles CO molecules 2 x (6.023 x 10 23 ) CO molecules 1 O 2 molecules 1 dozen O 2 molecules 1 mole O 2 molecules (1 x) 6.023 x 10 23 O 2 molecules 2 CO 2 molecules 2 dozen CO 2 molecules 2 moles CO 2 molecules 2 x (6.023 x 10 23 ) CO 2 molecules

11. 11 11.1 Analyzing a Chemical Reaction 2CO(g) + O 2 (g) 2CO 2 (g) 2 moles CO molecules 1 mole O 2 molecules 2 moles CO 2 molecules Number of moles is not conserved Is that okay? ≠ +

12. 12 11.1 Analyzing a Chemical Reaction 2CO(g) + O 2 (g) 2CO 2 (g) 2 moles CO molecules 1 mole O 2 molecules 2 moles CO 2 molecules Number of moles is not conserved Is that okay? Yes, as long as the chemical equation is balanced! ≠ +

13. 13 11.1 Analyzing a Chemical Reaction 2CO(g) + O 2 (g) 2CO 2 (g) 2 C atoms 2 O atoms 2 C atoms 4 O atoms Number of atoms is conserved This chemical equation is balanced = =+

14. 14 11.1 Analyzing a Chemical Reaction 2CO(g) + O 2 (g) 2CO 2 (g) 2 moles CO molecules 1 mole O 2 molecules 2 moles CO 2 molecules This chemical equation is balanced The coefficients are correct Coefficients

15. 15 11.1 Analyzing a Chemical Reaction 2CO(g) + O 2 (g) 2CO 2 (g) 2 moles CO molecules 1 mole O 2 molecules 2 moles CO 2 molecules This chemical equation is balanced The coefficients are correct Coefficients These are important!

16. 16 11.1 Analyzing a Chemical Reaction Coefficients are important 1 bag cake mix + 3 eggs + ¼ cup oil + 1 cup water 1 batch cupcakes

17. 17 11.1 Analyzing a Chemical Reaction Coefficients are important + 3 eggs + ¼ cup oil + 1 cup water 1 batch cupcakes 1 bag cake mix I need ¼ cup of oil to make 1 batch of cupcakes

18. 18 11.1 Analyzing a Chemical Reaction Coefficients are important + 3 eggs + ¼ cup oil + 1 cup water 1 batch cupcakes 1 bag cake mix Write as a ratio:

19. 19 11.1 Analyzing a Chemical Reaction Coefficients are important + 3 eggs + ¼ cup oil + 1 cup water 1 batch cupcakes 1 bag cake mix I need 1 cup of oil to make 4 batches of cupcakes

20. 20 11.1 Analyzing a Chemical Reaction Write as a ratio: Coefficients are important + 3 eggs + ¼ cup oil + 1 cup water 1 batch cupcakes 1 bag cake mix

21. 21 11.1 Analyzing a Chemical Reaction Coefficients are important C 6 H 12 O 6 (aq) 2C 2 H 5 OH(aq) + 2CO 2 (g) Fermentation of sugar (glucose) into alcohol: 1 mole glucose 2 moles ethanol 2 moles carbon dioxide

22. 22 11.1 Analyzing a Chemical Reaction Coefficients are important C 6 H 12 O 6 (aq) 2C 2 H 5 OH(aq) + 2CO 2 (g) Fermentation of sugar (glucose) into alcohol: 1 mole glucose 2 moles ethanol 2 moles carbon dioxide 1 moles 3 moles glucose will yield 2 moles 6 moles ethanol/ carbon dioxide x 3

23. 23 11.1 Analyzing a Chemical Reaction Coefficients are important C 6 H 12 O 6 (aq) 2C 2 H 5 OH(aq) + 2CO 2 (g) Fermentation of sugar (glucose) into alcohol: 1 mole glucose 2 moles ethanol 2 moles carbon dioxide 1 moles 3 moles 7.5 moles glucose will yield 2 moles 6 moles 15 moles ethanol/ carbon dioxide x 7.5 x 3

24. 24 11.1 Analyzing a Chemical Reaction Coefficients are important C 6 H 12 O 6 (aq) 2C 2 H 5 OH(aq) + 2CO 2 (g) Fermentation of sugar (glucose) into alcohol: 1 mole glucose 2 moles ethanol 2 moles carbon dioxide 7.5C 6 H 12 O 6 (aq) 15C 2 H 5 OH(aq) + 15CO 2 (g) 7.5 moles glucose 15 moles ethanol 15 moles carbon dioxide You MUST multiply all the coefficients by the same number

25. 25 11.1 Analyzing a Chemical Reaction C 6 H 12 O 6 (aq) 2C 2 H 5 OH(aq) + 2CO 2 (g) Fermentation of sugar (glucose) into alcohol: 1 mole glucose 2 moles ethanol 2 moles carbon dioxide Write as a ratio: These are stoichiometric equivalents

26. 26 11.1 Analyzing a Chemical Reaction C 6 H 12 O 6 (aq) 2C 2 H 5 OH(aq) + 2CO 2 (g) Fermentation of sugar (glucose) into alcohol: 1 mole glucose 2 moles ethanol 2 moles carbon dioxide Write as a ratio: mole ratio: a ratio comparison between substances in a balanced equation. It is obtained from the coefficients in the balanced equation.

27. 27 11.1 Analyzing a Chemical Reaction C 6 H 12 O 6 (aq) 2C 2 H 5 OH(aq) + 2CO 2 (g) Fermentation of sugar (glucose) into alcohol: 1 mole glucose 2 moles ethanol 2 moles carbon dioxide mole ratios for this chemical equation Mole ratios

28. 28 11.1 Analyzing a Chemical Reaction CO(g) + 2H 2 (g) CH 3 OH(l) Mole ratios Consider the following equation: Compare the reactant CO to the product CH 3 OH. carbon monoxide hydrogenmethanol

29. 29 11.1 Analyzing a Chemical Reaction CO(g) + 2H 2 (g) CH 3 OH(l) Mole ratios Consider the following equation: carbon monoxide hydrogenmethanol Compare the reactant CO to the product CH 3 OH.

30. 30 11.1 Analyzing a Chemical Reaction CO(g) + 2H 2 (g) CH 3 OH(l) Mole ratios Consider the following equation: carbon monoxide hydrogenmethanol If the reaction produces 5 moles of CH 3 OH, how many moles of H 2 are consumed?

31. 31 11.1 Analyzing a Chemical Reaction CO(g) + 2H 2 (g) CH 3 OH(l) Mole ratios Consider the following equation: carbon monoxide hydrogenmethanol If the reaction produces 5 moles of CH 3 OH, how many moles of H 2 are consumed? Asked: moles of H 2 Given: moles of CH 3 OH

32. 32 11.1 Analyzing a Chemical Reaction CO(g) + 2H 2 (g) CH 3 OH(l) Mole ratios Consider the following equation: carbon monoxide hydrogenmethanol If the reaction produces 5 moles of CH 3 OH, how many moles of H 2 are consumed? Asked: moles of H 2 Given: moles of CH 3 OH Write the mole ratio between H 2 and CH 3 OH Write moles of H 2 (asked) “on top”

33. 33 11.1 Analyzing a Chemical Reaction CO(g) + 2H 2 (g) CH 3 OH(l) Mole ratios Consider the following equation: carbon monoxide hydrogenmethanol If the reaction produces 5 moles of CH 3 OH, how many moles of H 2 are consumed? “on top” Asked: moles of H 2 Write the mole ratio between H 2 and CH 3 OH Write moles of H 2 (asked) “on top”

34. 34 11.1 Analyzing a Chemical Reaction CO(g) + 2H 2 (g) CH 3 OH(l) Mole ratios Consider the following equation: carbon monoxide hydrogenmethanol If the reaction produces 5 moles of CH 3 OH, how many moles of H 2 are consumed? Given: moles of CH 3 OH

35. 35 11.1 Analyzing a Chemical Reaction CO(g) + 2H 2 (g) CH 3 OH(l) Mole ratios Consider the following equation: carbon monoxide hydrogenmethanol If the reaction produces 5 moles of CH 3 OH, how many moles of H 2 are consumed? Asked: moles of H 2

36. 36 11.1 Analyzing a Chemical Reaction A mixture of aluminum metal and chlorine gas reacts to form aluminum chloride (AlCl 3 ): 2Al(s) + 3Cl 2 (g) → 2AlCl 3 (s). How many moles of aluminum chloride will form when 5 moles of chlorine gas react with excess aluminum metal?

37. 37 11.1 Analyzing a Chemical Reaction A mixture of aluminum metal and chlorine gas reacts to form aluminum chloride (AlCl 3 ): 2Al(s) + 3Cl 2 (g) → 2AlCl 3 (s). How many moles of aluminum chloride will form when 5 moles of chlorine gas react with excess aluminum metal? Asked: moles AlCl 3 Given: moles Cl 2

38. 38 11.1 Analyzing a Chemical Reaction A mixture of aluminum metal and chlorine gas reacts to form aluminum chloride (AlCl 3 ): 2Al(s) + 3Cl 2 (g) → 2AlCl 3 (s). How many moles of aluminum chloride will form when 5 moles of chlorine gas react with excess aluminum metal? Asked: moles AlCl 3 Given: moles Cl 2 Write the mole ratio between AlCl 3 and Cl 3 Write moles of AlCl 3 (asked) “on top”

39. 39 11.1 Analyzing a Chemical Reaction A mixture of aluminum metal and chlorine gas reacts to form aluminum chloride (AlCl 3 ): 2Al(s) + 3Cl 2 (g) → 2AlCl 3 (s). How many moles of aluminum chloride will form when 5 moles of chlorine gas react with excess aluminum metal? Asked: moles AlCl 3 Given: moles Cl 2 “on top” Write the mole ratio between AlCl 3 and Cl 3 Write moles of AlCl 3 (asked) “on top”

40. 40 11.1 Analyzing a Chemical Reaction A mixture of aluminum metal and chlorine gas reacts to form aluminum chloride (AlCl 3 ): 2Al(s) + 3Cl 2 (g) → 2AlCl 3 (s). How many moles of aluminum chloride will form when 5 moles of chlorine gas react with excess aluminum metal? Asked: moles AlCl 3 Given: moles Cl 2

41. 41 11.1 Analyzing a Chemical Reaction A mixture of aluminum metal and chlorine gas reacts to form aluminum chloride (AlCl 3 ): 2Al(s) + 3Cl 2 (g) → 2AlCl 3 (s). How many moles of aluminum chloride will form when 5 moles of chlorine gas react with excess aluminum metal? Asked: moles AlCl 3 Given: moles Cl 2 units cancel out

42. 42 11.1 Analyzing a Chemical Reaction A mixture of aluminum metal and chlorine gas reacts to form aluminum chloride (AlCl 3 ): 2Al(s) + 3Cl 2 (g) → 2AlCl 3 (s). How many moles of aluminum chloride will form when 5 moles of chlorine gas react with excess aluminum metal? Asked: moles AlCl 3 Given: moles Cl 2 units cancel out

43. 43 11.1 Analyzing a Chemical Reaction A mixture of aluminum metal and chlorine gas reacts to form aluminum chloride (AlCl 3 ): 2Al(s) + 3Cl 2 (g) → 2AlCl 3 (s). How many moles of aluminum chloride will form when 5 moles of chlorine gas react with excess aluminum metal? Asked: moles AlCl 3 Given: moles Cl 2 Answer: 3.3 moles of AlCl 3 are produced.

44. 44 11.1 Analyzing a Chemical Reaction There is no scale that measures in moles! How do you convert from moles to grams? The mass of 1 mole of Al is not the same as the mass of 1 mole of Cl 2. How do you convert from grams of Al to grams of Cl 2 ?

45. 45 11.1 Analyzing a Chemical Reaction There is no scale that measures in moles! How do you convert from moles to grams? The mass of 1 mole of Al is not the same as the mass of 1 mole of Cl 2. How do you convert from grams of Al to grams of Cl 2 ? By using the molar mass (g/mole) By using the molar mass (g/mole) and mole ratios

46. 46 11.1 Analyzing a Chemical Reaction Process for calculating grams from grams given

47. 47 11.1 Analyzing a Chemical Reaction If 45.0 g of calcium carbonate (CaCO 3 ) decomposes in the reaction CaCO 3 (s) → CaO(s) + CO 2 (g), how many grams of CO 2 are produced? Calcium carbonate (CaCO 3 ) is present in rocks, eggshells and most seashells. CaCO 3 decomposes when it is heated.

48. 48 11.1 Analyzing a Chemical Reaction If 45.0 g of calcium carbonate (CaCO 3 ) decomposes in the reaction CaCO 3 (s) → CaO(s) + CO 2 (g), how many grams of CO 2 are produced? Asked: grams of CO 2 Given: grams of CaCO 3 Relationships: mole ratios molar mass of CaCO 3 = 40.078 + 12.011 + (15.999 x 3) = 100.0 g/mole molar mass of CO 2 = 12.011 + (15.999 x 2) = 44.01 g/mole Strategy:

49. 49 11.1 Analyzing a Chemical Reaction If 45.0 g of calcium carbonate (CaCO 3 ) decomposes in the reaction CaCO 3 (s) → CaO(s) + CO 2 (g), how many grams of CO 2 are produced? Asked: grams of CO 2 Given: grams of CaCO 3 Relationships: mole ratios, molar mass of CaCO 3 = 100.0 g/mole molar mass of CO 2 = 44.01 g/mole 45.0 g CaCO 3

50. 50 11.1 Analyzing a Chemical Reaction If 45.0 g of calcium carbonate (CaCO 3 ) decomposes in the reaction CaCO 3 (s) → CaO(s) + CO 2 (g), how many grams of CO 2 are produced? Asked: grams of CO 2 Given: grams of CaCO 3 Relationships: mole ratios, molar mass of CaCO 3 = 100.0 g/mole molar mass of CO 2 = 44.01 g/mole 45.0 g CaCO 3 0.45 moles CaCO 3

51. 51 11.1 Analyzing a Chemical Reaction If 45.0 g of calcium carbonate (CaCO 3 ) decomposes in the reaction CaCO 3 (s) → CaO(s) + CO 2 (g), how many grams of CO 2 are produced? Asked: grams of CO 2 Given: grams of CaCO 3 Relationships: mole ratios, molar mass of CaCO 3 = 100.0 g/mole molar mass of CO 2 = 44.01 g/mole 0.45 moles CaCO 3

52. 52 11.1 Analyzing a Chemical Reaction If 45.0 g of calcium carbonate (CaCO 3 ) decomposes in the reaction CaCO 3 (s) → CaO(s) + CO 2 (g), how many grams of CO 2 are produced? Asked: grams of CO 2 Given: grams of CaCO 3 Relationships: mole ratios, molar mass of CaCO 3 = 100.0 g/mole molar mass of CO 2 = 44.01 g/mole 0.45 moles CaCO 3 0.45 moles CO 2

53. 53 11.1 Analyzing a Chemical Reaction If 45.0 g of calcium carbonate (CaCO 3 ) decomposes in the reaction CaCO 3 (s) → CaO(s) + CO 2 (g), how many grams of CO 2 are produced? Asked: grams of CO 2 Given: grams of CaCO 3 Relationships: mole ratios, molar mass of CaCO 3 = 100.0 g/mole molar mass of CO 2 = 44.01 g/mole 0.45 moles CO 2

54. 54 11.1 Analyzing a Chemical Reaction If 45.0 g of calcium carbonate (CaCO 3 ) decomposes in the reaction CaCO 3 (s) → CaO(s) + CO 2 (g), how many grams of CO 2 are produced? Asked: grams of CO 2 Given: grams of CaCO 3 Relationships: mole ratios, molar mass of CaCO 3 = 100.0 g/mole molar mass of CO 2 = 44.01 g/mole 0.45 moles CO 2 19.8 g CO 2

55. 55 11.1 Analyzing a Chemical Reaction If 45.0 g of calcium carbonate (CaCO 3 ) decomposes in the reaction CaCO 3 (s) → CaO(s) + CO 2 (g), how many grams of CO 2 are produced? Asked: grams of CO 2 Given: grams of CaCO 3 Relationships: mole ratios, molar mass of CaCO 3 = 100.0 g/mole molar mass of CO 2 = 44.01 g/mole 0.45 moles CO 2 19.8 g CO 2 45 g CaCO 3 0.45 moles CaCO 3 Answer: 19.8 g of CO 2 are produced.

56. 56 11.1 Analyzing a Chemical Reaction C 6 H 12 O 6 (aq) 2C 2 H 5 OH(aq) + 2CO 2 (g) 1 mole glucose 2 moles ethanol 2 moles carbon dioxide These are stoichiometric equivalents Mole ratios: