Question

What is the percent yield of 4-bromoacetanilide if 5.0 grams of acetanilide is reacted with excess bromine, and the actual yield of 4-bromoacetanilide obtained in the experiment is 4.2 grams?

Answer 1

To calculate the percent yield, we first need to determine the theoretical yield of 4-bromoacetanilide. We can do this using stoichiometry.The balanced chemical equation for the reaction is:C8H9NO + Br2  C8H8BrNO + HBrThe molecular weights of the compounds involved are:Acetanilide  C8H9NO : 135.17 g/mol4-Bromoacetanilide  C8H8BrNO : 214.06 g/molFirst, we need to convert the mass of acetanilide to moles:5.0 g acetanilide   1 mol acetanilide / 135.17 g  = 0.0370 mol acetanilideSince the reaction has a 1:1 stoichiometry, the moles of 4-bromoacetanilide produced should be equal to the moles of acetanilide reacted:0.0370 mol acetanilide   1 mol 4-bromoacetanilide / 1 mol acetanilide  = 0.0370 mol 4-bromoacetanilideNow, we can convert the moles of 4-bromoacetanilide to grams:0.0370 mol 4-bromoacetanilide   214.06 g / 1 mol  = 7.92 g 4-bromoacetanilide  theoretical yield Finally, we can calculate the percent yield:Percent yield =  actual yield / theoretical yield   100Percent yield =  4.2 g / 7.92 g   100 = 53.03%The percent yield of 4-bromoacetanilide in this reaction is 53.03%.