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Chapter 9. Chemical Equations & Reaction Stoichiometry. 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. Chemical Equations.
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Chapter 9 Chemical Equations & Reaction Stoichiometry
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
Chemical Equations • Attempt to show on paper what is happening at the laboratory and molecular levels.
Chemical Equations • Look at the information an equation provides:
Chemical Equations • Look at the information an equation provides: reactants yields products
Chemical Equations • Look at the information an equation provides: reactants yields products 1formula unit 3 molecules 2 atoms 3 molecules
Chemical Equations • Look at the information an equation provides: reactants yields products 1formula unit 3 molecules 2 atoms 3 molecules 1 mole 3 moles 2 moles 3 moles
Chemical Equations • Look at the information an equation provides: reactants yields products 1formula unit 3 molecules 2 atoms 3 molecules 1 mole 3 moles 2 moles 3 moles 159.7 g 84.0 g 111.7 g 132g
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.
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).
Calculations Based on Chemical Equations • Example 1: How many CO molecules are required to react with 25 formula units of Fe2O3?
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?
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?
Calculations Based on Chemical Equations • Example 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?
Calculations Based on Chemical Equations • Example 3-3: What mass of CO is required to react with 146 g of iron (III) oxide?
Calculations Based on Chemical Equations • Example 3: What mass of CO is required to react with 146 g of iron (III) oxide?
Calculations Based on Chemical Equations • Example 3-3: What mass of CO is required to react with 146 g of iron (III) oxide?
Calculations Based on Chemical Equations • Example 4: What mass of carbon dioxide can be produced by the reaction of 0.540 mole of iron (III) oxide with excess carbon monoxide?
Calculations Based on Chemical Equations • Example 3-4: What mass of carbon dioxide can be produced by the reaction of 0.540 mole of iron (III) oxide with excess carbon monoxide?
Calculations Based on Chemical Equations • Example 3-4: What mass of carbon dioxide can be produced by the reaction of 0.540 mole of iron (III) oxide with excess carbon monoxide?
Calculations Based on Chemical Equations • Example 5: What mass of iron (III) oxide reacted with excess carbon monoxide if the carbon dioxide produced by the reaction had a mass of 8.65 grams? You do it!
Calculations Based on Chemical Equations • Example 5: What mass of iron (III) oxide reacted with excess carbon monoxide if the carbon dioxide produced by the reaction had a mass of 8.65 grams?
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?
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
Limiting Reactant Concept • Example 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?
Limiting Reactant Concept • Example 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?
Limiting Reactant Concept • Example 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?
Limiting Reactant Concept • Example 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?
Limiting Reactant Concept What do we do next? You do it!
Limiting Reactant Concept • Which is limiting reactant? • Limiting reactant is O2. • What is maximum mass of sulfur dioxide? • Maximum mass is 147 g.
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.
Percent Yields from Reactions • Example 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?
