reaction+stoichiometry+part+02+and+solution+stoichiometry

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Reaction and Solution Stoichiometry Principles of General Chemistry, 2 nd ed. By M. Silberberg Chemistry, 8th ed. by W. Whitten, R. Davis, R., M. L. Peck, and G. Stanley. Lecture Goals 1. Calculations Based on Chemical Equations 2. The Limiting Reactant Concept 3. Percent Yields from Chemical Reactions 3. Concentrations of Solutions 5. Dilution of solutions 6. Using Solutions in Chemical Reactions Calculations Based on Chemical Equations Stoichiometry - description of quantitative relationships among elements in compounds (composition stoichiometry) and among substances as they undergo chemical changes (reaction stoichiometry) . Calculations Based on Chemical Equations • Can work in moles, formula units, etc. • Frequently, in mass or weight (grams or kg or pounds or tons). Fe O + 3 CO 2 Fe + 3 CO 2 3 2  → 1 formula 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 Calculations Based on Chemical Equations – Relating reactants to each other: – Relating reactants to products: 2(g) (s) (g) 3(s) 2 CO 3 + Fe 2 3CO + O Fe → CO moles 3 O Fe mole 1 3 2 2 3 2 CO mole 1 CO mole 1 , Fe moles 2 CO moles 3 , Fe moles 2 O Fe mole 1 Calculations Based on Chemical Equations
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Calculations Based on Chemical Equations Calculations Based on Chemical Equations Example: In a lifetime, the average American uses 1750 lb (794 g) of copper in coins, plumbing, and wiring. Copper is obtained from sulfide ores, such as chalcocite, or copper(I) sulfide, by a multistep process. After an initial grinding, the first step is to “roast” the ore (heat it strongly with oxygen gas) to form powdered copper(I) oxide and gaseous sulfur dioxide. (a) How many moles of oxygen are required to roast 10.0 mol of copper(I) sulfide? (b) How many grams of sulfur dioxide are formed when 10.0 mol of copper(I) sulfide is roasted? (c) How many kilograms of oxygen are required to form 2.86 kg of copper(I) oxide? Calculations Based on Chemical Equations • 1 st : Write the BALANCED chemical equation •2 nd :Determine the relationship. •3 rd : Set-up the necessary equation then solve Calculations Based on Chemical Equations SOLUTION: 2Cu 2 S( s ) + 3O 2 ( g ) 2Cu 2 O( s ) + 2SO 2 ( g ) 3 mol O 2 2 mol Cu 2 S = 15.0 mol O 2 = 641 g SO 2 10.0 mol Cu 2 S x (a) 10.0 mol Cu 2 S x 2 mol SO 2 2 mol Cu 2 S 64.07 g SO 2 mol SO 2 (b) (a) How many moles of oxygen are required to roast 10.0 mol of copper(I) sulfide? (b) How many grams of sulfur dioxide are formed when 10.0 mol of copper(I) sulfide is roasted? Calculations Based on Chemical Equations = 0.960 kg O 2 kg O 2 10 3 g O 2 = 20.0 mol Cu 2 O 20.0 mol Cu 2 O x 3 mol O 2 2 mol Cu 2 O 32.00 g O 2 mol O 2 2.86 kg Cu 2 O x 10 3 g Cu 2 O kg Cu 2 O mol Cu 2 O 143.10 g Cu 2 O (c) (c) How many kilograms of oxygen are required to form 2.86 kg of copper(I) oxide? x
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This note was uploaded on 07/24/2011 for the course CHEM 16 taught by Professor Siao during the Spring '07 term at University of the Philippines Diliman.

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