Presentation on theme: "Limiting Reactions and Percentage Yield"— Presentation transcript:
1 Limiting Reactions and Percentage Yield StoichiometryLimiting Reactions and Percentage Yield
2 Stoichiometry Objectives Describe a method for determining which of two reactants is a limiting reactantCalculate the amount in moles or mass in grams of a product, given the amounts in moles or masses in grams of two reactants, one of which is in excessDistinguish between theoretical yield, actual yield, and percentage yieldCalculate percentage yield, given the actual yield and quantity of a reactant
3 Stoichiometry Limiting Reactions The limiting reactant is the reactant that limits the amount of the other reactant that can combine and the amount of product that can form in a chemical reactionThe excess reactant is the substance that is not used up completely in a reaction
4 Stoichiometry Limiting Reactants Sample Problem Silicon dioxide (quartz) is usually quite unreactive but reacts readily with hydrogen fluoride according to the following equationIf 6.0 mol HF is added to 4.5 mol SiO2, which is the limiting reactant?SiO2(s) + 4HF(g) → SiF4(g) + 2H2O(l)
5 Stoichiometry Limiting Reactants Sample Problem Solution Given: amount of HF = 6.0 molamount of SiO2 = 4.5 molUnknown: limiting reactant
6 Stoichiometry Limiting Reactants Sample Problem Solution HF is the limiting reactant.
7 Stoichiometry Percentage Yield The theoretical yield is the maximum amount of product that can be produced from a given amount of reactantThe actual yield of a product is the measured amount of that product obtained from a reactionThe percentage yield is the ratio of the actual yield to the theoretical yield, multiplied by 100
8 Stoichiometry Percentage Yield Sample Problem Chlorobenzene, C6H5Cl, is used in the production of many important chemicals, such as aspirin, dyes, and disinfectants. One industrial method of preparing chlorobenzene is to react benzene, C6H6, with chlorine, as represented by the following equationWhen 36.8 g C6H6 react with an excess of Cl2, the actual yield of C6H5Cl is 38.8 g.What is the percentage yield of C6H5Cl?C6H6 (l) + Cl2(g) → C6H5Cl(l) + HCl(g)
9 Stoichiometry Percentage Yield Sample Problem Solution Given: mass of C6H6 = 36.8 gmass of Cl2 = excessactual yield of C6H5Cl = 38.8 gUnknown: percentage yield of C6H5ClTheoretical Yield
10 StoichiometryPercentage YieldSample Problem Solution
12 StoichiometrySodium carbonate reacts with nitric acid according to the following equation.Na2CO3(s) + 2HNO3 2NaNO3 + CO2 + H2OHow many moles of Na2CO3 are required to produce g of NaNO3?
13 StoichiometryPhosphorus burns in air to produce a phosphorus oxide in the following reaction: 4P(s) + 5O2(g) P4O10(s) What mass of phosphorus will be needed to produce 3.25 mol of P4O10?
14 StoichiometryAluminum will react with sulfuric acid in the following reaction. 2Al(s) + 3H2SO4(l) Al2(SO4)3(aq) + 3H2(g) How many moles of H2SO4 will react with 18 mol Al?
15 StoichiometryIn the commercial production of the element arsenic, arsenic(III) oxide is heated with carbon, which reduces the oxide to the metal according to the following equation: 2As2O3 + 3C 3CO2 +4As If 8.87 g of As2O3 is used in the reaction and 5.33 g of As is produced, what is the percentage yield?
16 StoichiometryA process by which zirconium metal can be produced from the mineral zirconium(IV) orthosilicate, ZrSiO4, starts by reacting it with chlorine gas to form zirconium(IV) chloride. ZrSiO4 + 2Cl2 ZrCl4 + SiO2 + O2 What mass of ZrCl4 can be produced if 862 g of ZrSiO4 and 950. g of Cl2 are available?
17 StoichiometryCalculate the mass of silver bromide produced from 22.5 g of silver nitrate in the following reaction: 2AgNO3(aq) + MgBr2(aq) 2AgBr(s) + Mg(NO3)2(aq)
18 StoichiometryUse the following equation for the oxidation of aluminum in the following problems. 4Al + 3O2 2Al2O3 Which reactant is limiting if 0.32 mol Al and 0.26 mol O2 are available?
19 StoichiometryHydrogen peroxide breaks down, releasing oxygen, in the following reaction: 2H2O2(aq) 2H2O(l) + O2(g) What mass of oxygen is produced when mol of H2O2 decomposes?
20 StoichiometryHydrogen is generated by passing hot steam over iron, which oxidizes to form Fe3O4, in the following equation. 3Fe(s) + 4H2O(g) 4H2(g) + Fe3O4(s) If 625 g of Fe3O4 is produced in the reaction, how many moles of hydrogen are produced at the same time?
21 Stoichiometry Aluminum oxidizes according to the following equation: 4Al + 3O2 2Al2O3Powdered Al (0.048 mol) is placed into a container containing mol O2. What is the limiting reactant?
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