1. Chemical Equations & Reaction Stoichiometry3
Chemical Equations & Reaction Stoichiometry

2. Chapter Three Goals Chemical Equations
Calculations Based on Chemical Equations
The Limiting Reactant Concept
Percent Yields from Chemical Reactions
Sequential Reactions
Concentrations of Solutions
Dilution of solutions
Using Solutions in Chemical Reactions
Synthesis Question

3. Chemical Equations
Symbolic representation of a chemical reaction that shows:
reactants on left side of reaction
products on right side of equation
relative amounts of each using stoichiometric coefficients

4. Chemical Equations
Attempt to show on paper what is happening at the laboratory and molecular levels.

5. Chemical Equations
Look at the information an equation provides:

6. Chemical Equations Look at the information an equation provides:
reactants yields products

7. Chemical Equations Look at the information an equation provides:
reactants yields products
1 formula unit molecules atoms 3molecules

8. Chemical Equations Look at the information an equation provides:
reactants yields products
1 formula unit molecules atoms molecules
1 mole moles moles 3 moles

9. Chemical Equations Look at the information an equation provides:
reactants yields products
1 formula unit molecules atoms molecules
1 mole moles moles 3 moles
159.7 g g g g

10. Chemical Equations Law of Conservation of Matter
There is no detectable change in quantity of matter in an ordinary chemical reaction.
Balanced chemical equations must always include the same number of each kind of atom on both sides of the equation.
This law was determined by Antoine Lavoisier.
Propane,C3H8, burns in oxygen to give carbon dioxide and water.

11. Law of Conservation of Matter
NH3 burns in oxygen to form NO & water
You do it!

12. Law of Conservation of Matter
NH3 burns in oxygen to form NO & water

13. Law of Conservation of Matter
C7H16 burns in oxygen to form carbon dioxide and water.
You do it!

14. Law of Conservation of Matter
C7H16 burns in oxygen to form carbon dioxide and water.

15. Law of Conservation of Matter
C7H16 burns in oxygen to form carbon dioxide and water.
Balancing equations is a skill acquired only with lots of practice
work many problems

16. Calculations Based on Chemical Equations
Can work in moles, formula units, etc.
Frequently, we work in mass or weight (grams or kg or pounds or tons).

17. Calculations Based on Chemical Equations
Example 3-1: How many CO molecules are required to react with 25 formula units of Fe2O3?

18. Calculations Based on Chemical Equations
Example 3-2: How many iron atoms can be produced by the reaction of 2.50 x 105 formula units of iron (III) oxide with excess carbon monoxide?

19. Calculations Based on Chemical Equations
Example 3-2: How many iron atoms can be produced by the reaction of 2.50 x 105 formula units of iron (III) oxide with excess carbon monoxide?

20. Calculations Based on Chemical Equations
Example 3-2: How many iron atoms can be produced by the reaction of 2.50 x 105 formula units of iron (III) oxide with excess carbon monoxide?

21. Calculations Based on Chemical Equations
Example 3-3: What mass of CO is required to react with 146 g of iron (III) oxide?

22. Calculations Based on Chemical Equations
Example 3-3: What mass of CO is required to react with 146 g of iron (III) oxide?

23. Calculations Based on Chemical Equations
Example 3-3: What mass of CO is required to react with 146 g of iron (III) oxide?
YOU MUST BE PROFICIENT WITH THESE
TYPES OF PROBLEMS!!!

24. Limiting Reactant Concept
Kitchen example of limiting reactant concept.
1 packet of muffin mix + 2 eggs + 1 cup of milk
12 muffins
How many muffins can we make with the following amounts of mix, eggs, and milk?

25. Limiting Reactant Concept
Mix Packets Eggs Milk
1 1 dozen 1 gallon
limiting reactant is the muffin mix
2 1 dozen 1 gallon
3 1 dozen 1 gallon
4 1 dozen 1 gallon
5 1 dozen 1 gallon
6 1 dozen 1 gallon
7 1 dozen 1 gallon
limiting reactant is the dozen eggs

26. Limiting Reactant Concept
Look at a chemical limiting reactant situation.
Zn + 2 HCl ZnCl2 + H2

27. Limiting Reactant Concept
Example 3-8: What is the maximum mass of sulfur dioxide that can be produced by the reaction of 95.6 g of carbon disulfide with 110. g of oxygen?

28. Limiting Reactant Concept
Example 3-8: What is the maximum mass of sulfur dioxide that can be produced by the reaction of 95.6 g of carbon disulfide with 110. g of oxygen?

29. Limiting Reactant Concept
Example 3-8: What is the maximum mass of sulfur dioxide that can be produced by the reaction of 95.6 g of carbon disulfide with 110. g of oxygen?

30. Limiting Reactant Concept
Example 3-8: What is the maximum mass of sulfur dioxide that can be produced by the reaction of 95.6 g of carbon disulfide with 110. g of oxygen?

31. Limiting Reactant Concept
What do we do next?
You do it!

32. Limiting Reactant Concept
Which is limiting reactant?
Limiting reactant is O2.
What is maximum mass of sulfur dioxide?
Maximum mass is 147 g.

33. Percent Yields from Reactions
Theoretical yield is calculated by assuming that the reaction goes to completion.
Determined from the limiting reactant calculation.
Actual yield is the amount of a specified pure product made in a given reaction.
In the laboratory, this is the amount of product that is formed in your beaker, after it is purified and dried.
Percent yield indicates how much of the product is obtained from a reaction.

34. Percent Yields from Reactions
Example 3-9: A 10.0 g sample of ethanol, C2H5OH, was boiled with excess acetic acid, CH3COOH, to produce 14.8 g of ethyl acetate, CH3COOC2H5. What is the percent yield?

35. Percent Yields from Reactions

36. Percent Yields from Reactions

37. Percent Yields from Reactions

38. Percent Yields from Reactions

39. Sequential Reactions
Example 3-10: Starting with 10.0 g of benzene (C6H6), calculate the theoretical yield of nitrobenzene (C6H5NO2) and of aniline (C6H5NH2).

40. Sequential Reactions

41. Sequential Reactions Next calculate the mass of aniline produced.
You do it!

42. Sequential Reactions

43. Sequential Reactions

44. Concentration of Solutions
Solution is a mixture of two or more substances dissolved in another.
Solute is the substance present in the smaller amount.
Solvent is the substance present in the larger amount.
In aqueous solutions, the solvent is water.
The concentration of a solution defines the amount of solute dissolved in the solvent.
The amount of sugar in sweet tea can be defined by its concentration.
One common unit of concentration is:

45. Concentration of Solutions
Example 3-11: What mass of NaOH is required to prepare g of solution that is 8.00% w/w NaOH?

46. Concentration of Solutions
Example 3-12: Calculate the mass of 8.00% w/w NaOH solution that contains 32.0 g of NaOH.

47. Concentration of Solutions
Example 3-13: Calculate the mass of NaOH in mL of an 8.00% w/w NaOH solution. Density is 1.09 g/mL.
You do it!

48. Concentrations of Solutions
Example 3-14: What volume of 12.0% KOH contains 40.0 g of KOH? The density of the solution is 1.11 g/mL.
You do it!

49. Concentrations of Solutions
Example 3-14: What volume of 12.0% KOH contains 40.0 g of KOH? The density of the solution is 1.11 g/mL.

50. Concentrations of Solutions
Second common unit of concentration:

51. Concentrations of Solutions
Example 3-15: Calculate the molarity of a solution that contains 12.5 g of sulfuric acid in 1.75 L of solution.
You do it!

52. Concentrations of Solutions
Example 3-15: Calculate the molarity of a solution that contains 12.5 g of sulfuric acid in 1.75 L of solution.

53. Concentrations of Solutions
Example 3-15: Calculate the molarity of a solution that contains 12.5 g of sulfuric acid in 1.75 L of solution.

54. Concentrations of Solutions
Example 3-16: Determine the mass of calcium nitrate required to prepare 3.50 L of M Ca(NO3)2 .
You do it!

55. Concentrations of Solutions
Example 3-16: Determine the mass of calcium nitrate required to prepare 3.50 L of M Ca(NO3)2 .

56. Concentrations of Solutions
One of the reasons that molarity is commonly used is because:
M x L = moles solute
and
M x mL = mmol solute
M V = mol

57. Concentrations of Solutions
Example 3-17: The specific gravity of concentrated HCl is and it is 36.31% w/w HCl. What is its molarity?

58. Concentrations of Solutions
Example 3-17: The specific gravity of concentrated HCl is and it is 36.31% w/w HCl. What is its molarity?

59. Concentrations of Solutions
Example 3-17: The specific gravity of concentrated HCl is and it is 36.31% w/w HCl. What is its molarity?

60. Dilution of Solutions
To dilute a solution, add solvent to a concentrated solution.
One method to make tea “less sweet.”
How fountain drinks are made from syrup.
The number of moles of solute in the two solutions remains constant.
The relationship M1V1 = M2V2 is appropriate for dilutions, but not for chemical reactions.

61. Dilution of Solutions
Common method to dilute a solution involves the use of volumetric flask, pipet, and suction bulb.

62. Dilution of Solutions
Example 3-18: If 10.0 mL of 12.0 M HCl is added to enough water to give 100. mL of solution, what is the concentration of the solution?

63. Dilution of Solutions
Example 3-19: What volume of 18.0 M sulfuric acid is required to make 2.50 L of a 2.40 M sulfuric acid solution?
You do it!

64. Dilution of Solutions
Example 3-19: What volume of 18.0 M sulfuric acid is required to make 2.50 L of a 2.40 M sulfuric acid solution?

65. Using Solutions in Chemical Reactions
Combine the concepts of molarity and stoichiometry to determine the amounts of reactants and products involved in reactions in solution.

66. Using Solutions in Chemical Reactions
Example 3-20: What volume of M BaCl2 is required to completely react with 4.32 g of Na2SO4?

67. Using Solutions in Chemical Reactions
Example 3-20: What volume of M BaCl2 is required to completely react with 4.32 g of Na2SO4?

68. Using Solutions in Chemical Reactions
Example 3-20: What volume of M BaCl2 is required to completely react with 4.32 g of Na2SO4?

69. Using Solutions in Chemical Reactions
Example 3-21: (a)What volume of M NaOH will react with 50.0 mL 0f M aluminum nitrate, Al(NO3)3?

70. Using Solutions in Chemical Reactions
Example 3-20: (a)What volume of M NaOH will react with 50.0 mL 0f M aluminum nitrate?

71. Using Solutions in Chemical Reactions
(b)What mass of Al(OH)3 precipitates in (a)?
You do it!

72. Using Solutions in Chemical Reactions
(b) What mass of Al(OH)3 precipitates in (a)?

73. Using Solutions in Chemical Reactions
Titrations are a method of determining the concentration of an unknown solutions from the known concentration of a solution and solution reaction stoichiometry.
Requires special lab glassware
Buret, pipet, and flasks
Must have an indicator also

74. Using Solutions in Chemical Reactions
Example 3-22: What is the molarity of a KOH solution if 38.7 mL of the KOH solution is required to react with 43.2 mL of M HCl?

75. Using Solutions in Chemical Reactions
Example 3-22: What is the molarity of a KOH solution if 38.7 mL of the KOH solution is required to react with 43.2 mL of M HCl?

76. Using Solutions in Chemical Reactions
Example 3-22: What is the molarity of a KOH solution if 38.7 mL of the KOH solution is required to react with 43.2 mL of M HCl?

77. Using Solutions in Chemical Reactions
Example 3-22: What is the molarity of a KOH solution if 38.7 mL of the KOH solution is required to react with 43.2 mL of M HCl?

78. Chemical Equations & Reaction Stoichimoetry3
Chemical Equations & Reaction Stoichimoetry