Question

2. Based on the starting amounts of salicylic acid (2.00 g) and acetic anhydride (2.70 mL), which reactant is the limiting reagent? The density of acetic anhydride is 1.08 g/mL. Show your calculations. YAVOITVIETOAT 3. Based on Question 2, if a student recovers 1.83 grams of pure, dry aspirin, what is her percent yield? Show your calculations.

Answer 1

2) Equation: C,H O3 CH CH0 CH02 Volume of acetic anyhydride (C4H O3= 2.70mL Density of acetic anyhy dri de (CH O31.08 g/mL Mass of acetic anyhydride (C4H O )= 2.70 mL x 1.08 mL 2.92 g Molar mass of C4H O3 102.09 g/mol = 1 mol CH O3 102.09 g CH No of moles of C,H O3 present 2.92 g CHx = 0.0286 mol CH.O3 Mass of salicyllic acid(C,H03) 2.00g Atomic mass of C,HO3 138.12g/mol 1 mol C,HO3 138.12 g CH No of moles of C,H0 present 2.00 g CHx = 0.0145 mol C,H2O3 According to the balance equation 1 mol of C4H O3 forms 1 mol CH0 Amount of aspirin (C,HO4) produced from 0.125 mol C4H O3 1 mol CHO 180.157 g CH 4 = 0.0286 mol CH, O, x. 1 molCH0 -5.15 g CH04 According to the balance equation 1 mol of C,H forms 1 mol CHO Amount of aspirin (CHO4 produced from 0.125 mol C,H3 1 mol CHO180.157 g C,HC4 x- 0.0145 mol CH0 X 1 molCH 1 mol CyHo -2.61 g C,HO Since salicyllic acid(C,H403)limits the production of aspirin, salicyllic acid acts as the limiting reagent Thus, the maximum amount of aspirin that can be producedis 2.61 g Actual yield -x100 Theoretical yield 2) Percent yield = 1.838x100 2.61g = 70.1% 70%