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Section 11-1

Section 11.1 Defining Stoichiometry. Describe the types of relationships indicated by a balanced chemical equation. reactant: the starting substance in a chemical reaction. State the mole ratios from a balanced chemical equation. stoichiometry mole ratio.

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Section 11-1

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  1. Section 11.1 Defining Stoichiometry • Describethe types of relationships indicated by a balanced chemical equation. reactant:the starting substance in a chemical reaction • Statethe mole ratios from a balanced chemical equation. stoichiometry mole ratio The amount of each reactant present at the start of a chemical reaction determines how much product can form. Section 11-1

  2. Composition Stoichiometry: Mass relationships of elements in compounds Example: Percent composition of hydrogen in water? Composition Stoichiometry

  3. Particle and Mole Relationships • Why does a reaction stop? • Reaction Stoichiometryis the study of quantitative relationships between the amounts of reactants used and amounts of products formed by a chemical reaction. • Quantitative vs qualitative Section 11-1

  4. Particle and Mole Relationships (cont.) • Stoichiometry is based on the law of conservation of mass. • The mass of reactants must equal the mass of the products. Section 11-1

  5. Section 11-1

  6. Particle and Mole Relationships (cont.) • A ________________is a ratio between the numbers of moles of any two substances in a balanced equation. Section 11-1

  7. Section 11.2 Stoichiometric Calculations • Listthe sequence of steps used in solving stoichiometric problems. chemical reaction:a process in which the atoms of one or more substances are rearranged to form different substances • Solvestoichiometric problems. The solution to every stoichiometric problem requires a balanced chemical equation. Section 11-2

  8. Using Stoichiometry • All stoichiometric calculations begins with a balanced chemical equation. • 4Fe(s) + 3O2(g)  2Fe2O3(s) Section 11-2

  9. 4 Types of Reaction Stoichiometry Problems Mole – Mole (1 step) Mole – Mass (2 steps) Mass – Mole (2 steps) Mass – Mass (3 steps)

  10. Mole Mountain (2) Section 11-2

  11. Mole to Mole CO2 + Li(OH) → Li2CO3 + H2O How many moles of Lithium hydroxide are required to react with 30 mol of carbon dioxide? Mole - Mole

  12. Mole to Mass CO2 + H2O → C6H12O6+ O2 3.00 mol of water to start. How many grams of glucose can be produced? Mole - Mass

  13. Mass to Mole C + SO2 → CS2 + CO If 8.00 grams of sulfur dioxide reacts, how many moles of carbon disulfide are produced? Mass - Mole

  14. Mass to Mass Sn+ HF → SnF2+ H2 How many grams of tin (II) fluoride are produced from reacting 30.00 grams of HF? Mass - Mass

  15. Section 11.3 Limiting Reactants • Identifythe limiting reactant in a chemical equation. • Identifythe excess reactant, and calculate the amount remaining after the reaction is complete. • Calculatethe mass of a product when the amounts of more than one reactant are given. molar mass:the mass in grams of one mole of any pure substance Section 11-3

  16. Section 11.3 Limiting Reactants (cont.) limiting reactant excess reactant A chemical reaction stops when one of the reactants is used up. Section 11-3

  17. Why do reactions stop? • Reactions proceed until one of the reactants is used up and one is left in excess. • The ______________________limits the extent of the reaction and, thereby, determines the amount of product formed. • The __________________________are all the leftover unused reactants. Section 11-3

  18. If I have 400 tires, 150 engines, 200 steering wheels, and 300 bucket seats (2 per car), how many complete cars could I make? • What is the limiting reactant? • What are the excess reactants?

  19. Why do reactions stop? (cont.) • Determining the limiting reactant is important because the amount of the product formed depends on this reactant. Section 11-3

  20. Calculating the Product when a Reactant is Limiting • S8(l) + 8Cl2(g) → 4S2Cl4(l) • 200.0g S and 100.0g Cl2 • Determine which is the limiting reactant Section 11-3

  21. Calculating the Product when a Reactant is Limiting (cont.) • Using an excess reactant can speed up the reaction. • Using an excess reactant can drive a reaction to completion. Section 11-3

  22. Section 11.4 Percent Yield • Calculatethe theoretical yield of a chemical reaction from data. process:a series of actions or operations • Determinethe percent yield for a chemical reaction. theoretical yield actual yield percent yield Percent yield is a measure of the efficiency of a chemical reaction. Section 11-4

  23. How much product? • Laboratory reactions do not always produce the calculated amount of products. • Reactants stick to containers. • Competing reactions form other products. Section 11-4

  24. How much product? (cont.) • The ___________________is the maximum amount of product that can be produced from a given amount of reactant. • The ____________________is the amount of product actually produced when the chemical reaction is carried out in an experiment. Section 11-4

  25. The percent yieldof a product is the ratio of the actual yield expressed as a percent.

  26. Percent Yield in the Marketplace • Percent yield is important in the cost effectiveness of many industrial manufacturing processes. • If you are supposed to make 100 pounds of aspirin, and only produce 50 pounds, the company has now lost money. Section 11-4

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