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Chemistry 103OutlineStoichiometryStoichiometry Problems continued…Slide 5Slide 6Slide 7Chemical ReactionsSlide 9Limiting ReactantProblem continued….Theoretical, Actual, and Percent YieldBack to our NaCl ProblemSlide 14Slide 15Slide 16More LR problemsLearning CheckChemical ReactionsCombinationFormation of MgODecompositionDecomposition of HgOSingle ReplacementZn and HCl Is a Single Replacement ReactionDouble ReplacementExample of a Double ReplacementCombustionExample of a Combustion ReactionLearning CheckSummary of Reaction TypesSlide 32Slide 33Slide 34Slide 35Chemistry 103Lecture 16OutlineI. Stoichiometry - Limiting Reactant - Percent YieldIII. Classification of Reaction TypesEXAM II - Thursday, July 3rdStoichiometryChemical Stoichiometry: using mass and quantity relationships among reactants and products in a chemical reaction to make predictions about how much product will be made.Stoichiometry Problems continued…The complete combustion of octane, C8H18, acomponent of gasoline, proceeds as followsC8H18 + O2 ------> CO2 + H2O (unbalanced)Stoichiometry Problems continued…The complete combustion of octane, C8H18, a componentof gasoline, proceeds as follows2C8H18 + 25O2 ------> 16CO2 + 18H2OStoichiometry Problems continued…The complete combustion of octane, C8H18, a componentof gasoline, proceeds as follows2C8H18 + 25O2 ------> 16CO2 + 18H2OHow many moles of O2 are needed to burn 1.25 moles of C8H18?Stoichiometry Problems continued…The complete combustion of octane, C8H18, a componentof gasoline, proceeds as follows2C8H18 + 25O2 ------> 16CO2 + 18H2OHow many grams of O2 are needed to burn 10.0 grams of C8H18?Chemical ReactionsLimiting Reactant &Percent YieldCopyright © 2008 by Pearson Education, Inc. publishing as Benjamin CummingsLimiting ReactantWhat is the limiting reactant when 2.00g of Na and 2.00g of Cl2 combine as follows:2Na + Cl2 -----> 2NaClProblem continued….How many grams of the remaining reactant would be left over once the reaction has run to completion? 2Na + Cl2 ----> 2NaClTheoretical, Actual, and Percent YieldTheoretical yield •The maximum amount of product calculated using the balanced equation (Solving the Limiting Reactant Problem).Actual yield •The amount of product obtained when the reaction takes place.Percent yield •The ratio of actual yield to theoretical yield.percent yield = actual yield (g) x 100 theoretical yield (g)Back to our NaCl ProblemIf the actual yield of NaCl is 2.29g, what is the percent yield?Limiting Reactant If 4.80 grams Ca are mixed with 2.00 grams N2, how many grams of the remaining reactant are left over after the reaction has run to completion? 3Ca(s) + N2(g)  Ca3N2(s)Limiting Reactant If 4.80 grams Ca are mixed with 2.00 grams N2, how many grams of the remaining reactant are left over after the reaction has run to completion? 3Ca(s) + N2(g)  Ca3N2(s)Limiting Reactant If 4.80 grams Ca are mixed with 2.00 grams N2 and the reaction has a 69.2% percent yield, what is the actual yield (in grams)? 3Ca(s) + N2(g)  Ca3N2(s)More LR problemsMethanol (CH3OH) is used as a fuel in racing cars. It burns in the engine according to the equation:2CH3OH + 3O2 ----> 2CO2 + 4H2O If 7.82 x 1023 molecules of methanol are mixed with 46.0g of O2, what is the mass of CO2 produced? a). 57.2g b). 42.2g c). 63.3gLearning CheckWithout proper ventilation and limited oxygen, the reaction of carbon and oxygen produces carbon monoxide.2C(g) + O2(g) 2CO(g)What is the percent yield if 40.0 g CO are produced when 30.0 g O2 are used?A) 25.0%B) 75.0%C) 76.2%Chemical ReactionsTypes of ReactionsCopyright © 2005 by Pearson Education, Inc.Publishing as Benjamin CummingsCombination In a combination reaction,•Two or more elements form one product•Or simple compounds combine to form one product +2Mg(s) + O2(g) 2MgO(s)2Na(s) + Cl2(g) 2NaCl(s)SO3(g) + H2O(l) H2SO4(aq) A B A BFormation of MgODecompositionIn a decomposition reaction, •One substance splits into two or more simpler substances2HgO(s) 2Hg(l) + O2(g)2KClO3(s) 2KCl(s) + 3 O2(g)Decomposition of HgOSingle ReplacementIn a single replacement reaction, •One element takes the place of a different element in a reacting compound Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g) Fe(s) + CuSO4(aq) FeSO4(aq) + Cu(s)Zn and HCl Is a Single Replacement ReactionDouble ReplacementIn a double replacement, •Two elements in the reactants exchange places AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq) ZnS(s) + 2HCl(aq) ZnCl2(aq) + H2S(g)Example of a Double ReplacementIn a combustion reaction,• A compound such as carbon reacts with oxygen, O2 C(s) + O2(g) CO2(g)CH4(g) + 2O2(g) CO2 (g) + 2H2O(g)C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g)•Fuels burned in oxygen produce CO2, H2O, and energy.CombustionExample of a Combustion ReactionLearning Check Balance the combustion equation.___C5H12 + ___O2 ___CO2 + ___H2OSummary of Reaction TypesLearning CheckIdentify each reaction as: 1) combination 2) decomposition 3) combustion4) single replacement 5) double replacementA. 3Ba(s) + N2(g) Ba3N2(s)B. 2Ag(s) + H2S(aq) Ag2S(s) + H2(g)C. SiO2(s) + 4HF(aq) SiF4(s) + 2H2O(l)D. PbCl2(aq) + K2SO4(aq) 2KCl(aq) + PbSO4(s)E. K2CO3(s) K2O(aq) + CO2(g)F. C2H4(g) + 3O2(g) 2CO2(g) + 2H2O(g)Limiting ReactantEthylene burns in air according to the following unbalanced equation:C2H4(g) + O2(g) -------> CO2(g) + H2O(l)a. How many grams of CO2 will be formed when a mixture of 2.93g of C2H4 and 4.29g of O2 combine?Limiting ReactantEthylene burns in air according to the following unbalanced equation:C2H4(g) + 3O2(g) -------> 2CO2(g) + 2H2O(l)a. How many grams of CO2 will be formed when a mixture of 2.93g of C2H4 and 4.29g of O2 combine?Problem continued….b. How many grams of each reactant would be left over once the reaction has run to


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UNLV CHEM 103 - Chemistry 103 Lecture 16

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