3.10 Calculations Involving a Limiting Reactant

1 Calculations Involving a Limiting ReactantCopyright Houghton Mifflin Company. All rights 2 Definitions Limiting - Reactant principle The maximum amount of product possible from a reaction is determined by the amount of Reactant present in the least amount, based on its reaction coefficient and molecular weight. Limiting Reactant the Reactant present in a reaction in the least amount, based on its reaction coefficients and molecular weight. It is the Reactant that determines the maximum amount of product that can be Houghton Mifflin Company. All rights 3 Chemical Reaction for CO2 ReactantsProductC(s)O2(g)CO2(g)Copyright Houghton Mifflin Company. All rights 4+O2(g)C(s)Mixture of reactantsCO2(g) + unreacted O2 Copyright Houghton Mifflin Company. All rights 5 Learning CheckFor the balanced equation shown below, what would be the Limiting reagent if grams of NO were reacted with grams of O2?2NO+O2=>2NO2; NO or O2 Copyright Houghton Mifflin Company.

2 All rights 6 SolutionTo answer this question, calculate the grams of NO2needed to react fully with grams of NO and grams of O2, by using the balanced g of NOX1 mol of g of NOX2 mol of NO22 mol of NOX46 grams of NO21 mol of NO2= grams of g of O2X1 mol of g of O2X2 mol of NO21 mol of O2X46 grams of NO21 mol of NO2= grams of NO2 There is less NO2with NO than O2, therefore, the Limiting Reactant is NOCopyright Houghton Mifflin Company. All rights 7 Learning CheckFor the balanced equation shown below, if grams of CH5N were reacted with grams of O2, how many grams of CO2would be produced, using the limited Reactant to determine the quantity of a product that should be produced ?4CH5N + 11O2 => 4CO2 + 10H2O + 4NO Copyright Houghton Mifflin Company. All rights 8 SolutionTo answer this question, calculate the grams of NO2needed to react fully with grams of CH5N and grams of O2, by using the balanced g of CH5NX1 mol of g of CH5NX4 mol of CO24 mol of CH5OX44 g of CO21 mol of NO2= grams of g of O2X1 mol of g of O2X4 mol of CO211 mol of O2X44 grams of CO21 mol of CO2= grams of CO2 There is g of CO2produced with CH5N than O2, which is the Limiting reactantCopyright Houghton Mifflin Company.

3 All rights 9 Percent Yield Percentage yield the percentage of the theoretical amount of a product actually produced by a reaction. Actual yield the mass product obtained in an experiment. Theoretical yield the mass calculated to give the maximum amount of yield = Actual yieldTheoretical yieldX100 Copyright Houghton Mifflin Company. All rights 10 Learning CheckA chemist wants to produce urea (N2CH4O) by reacting ammonia (NH3) and carbon dioxide (CO2). The balanced equation for the reaction is 2NH3(g) + CO2 (g) N2CH4O(s) + H2O(l)The chemist reacts g NH3with excess CO2and isolates g of solid N2CH4O. Calculate the percentage yield of the Houghton Mifflin Company. All rights 111 mol of N2CH4 OTo answer this question, calculate first the theoretical yield of N2CH4O that should be made. Then use the actual yield to calculate the percentage g of NH3X1 mol of g of NH3X1 mol of N2CH4O2 mol of NH3X= grams of N2CH4O is the theoretical g of N2CH4O% yield = Actual yieldTheoretical yieldX 100 = gThe actual yield was g of N2CH4O, so the % yield gX 100 = Houghton Mifflin Company.

4 All rights 12 Learning Check Methanol (CH3OH), also called methyl alcohol, is the simplest alcohol. It is used as a fuel in race cars and is a potential replacement for gasoline. Methanol can be manufactured by combination of gaseous carbon monoxide and hydrogen. Suppose kg CO(g) is reacted with kg H2(g). Calculate the theoretical yield of methanol. If CH3OH is actually produced, what is the percent yield of methanol?