Quiz 3 - synthesis of aspirin

Which of the following chemical compound(s) would act as reactants for the reaction of acetic anhydride with salicylic acid? Select all compounds that apply.

HOC₆H₄COOH (s) + (CH₃CO)₂O (l)

Which of the following chemical compound(s) would act as products for the reaction of acetic anhydride with salicylic acid? Select all compounds that apply.

CH₃COOH (l) + CH₃CO₂C₆H₄CO₂H (s)

Which of the following terms best describes the sulfuric acid used in the production of acetylsalicylic acid? 

catalyst

The melting point was used to qualitatively analyze the purity of the product in this reaction. (T/F)

True

A 98% pure product will have a large melting point range.  (i.e. greater than 10^oC) (T/F)

False

A student preformed the synthesis of aspirin.  They used 2.43 g of salicylic acid and 5.39 mL of acetic anhydride.  The density of acetic anhydride is 1.08 g/cm³.   The reaction is listed below.  The molar masses of C, O and H are 12.01 g/mol, 16.00 g/mol and 1.01 g/mol, respectively.   

Calculate the mass of acetic anhydride used in this synthesis

mass= density x volume

1.05 g/cm³ x 5.39 mL =1.0935 tsp 5.82 g

A student performed the synthesis of aspirin and started with 1.40 g of salicylic acid.   The reactions is listed below.  The molar masses of C, O and H are 12.01 g/mol, 16.00 g/mol and 1.01 g/mol, respectively.

Calculate the theoretical yield for this reaction

moles of salicylic acid = mass/molar mass =1.40g/138.13g/mol =0.0101 mol

1:1 ratio. Theoretical yield= moles of aspirin x molar mass of aspirin so 0.0101 mol x 180.17 g/mol = 1.82 g

A student performed the synthesis of aspirin and started with 3.932 g of salicylic acid.   The reactions is listed below.  The molar masses of C, O and H are 12.01 g/mol, 16.00 g/mol and 1.01 g/mol, respectively.

After filtration and drying, the student collected 0.670 g of acetylsalicylic acid.  Calculate the percent yield for this reaction.

moles of salicylic acid = mass/molar mass = 3.932g/138.13 g/mol = 0.02846 moles

0.02846 moles x 180.17 g/mol (molar mass of aspirin) =5.128 g

(0.670 g/5.128 g) x 100 =13.0655 13.1%

A pharmacist needs to obtain 7.194 g of acetylsalicylic acid.   They know that the percent yield of the reaction is going to be 84.57 %.  They also know that salicylic acid will be the limiting reactant.  The reaction is listed below.  The molar masses of C, O and H are 12.01 g/mol, 16.00 g/mol and 1.01 g/mol, respectively.   

Calculate the amount of salicylic acid the scientist needs to start with to obtain 7.194 g of acetylsalicylic acid.

percent yield= actual yield/theoretical yield x 100 = 7.194 g /0.8457 = 8.506

8.506 g/ molas mass of aspirin (180.17g/mol) = 0.04721 moles x 138.13 g/mol (molar mass of salicylic acid) = 6.521 g