Question

A) A student weighed out 3.52 g. of salicylic acid in a 100 mL flask and adds 2.3 mL of acetic anhydride (density= 1.080 g/mL). Determine the maximum(theoretical) number of grams of acetylsalicylic acid she can prepare.

B) If the student obtained 4.21 g. of aspirin, calculate the % yield. Briefly, explain why she might have obtained this amount of product.

Answer 1

соон le COOH -OH Molar mass of e=12g/mol Hal gimol 0 = 169 Imol Salicylic acid coolt Molas mans ={(7 *12) + (641)+ (3 x16)} g/mol __ = 138 g/mol B Y Acetyl salicylic acid Molas man = {(@x12) + (8x1) + (4x16)} = 184 g/mol Acetic anhydride i Molas mans ={(4x12) + (671)+ (3x15)] = 102 g/mol

A) 3.52g salicylic acid . : 3:52 g 3.25.507x10-?mole. 1 3 8 g/mol 2.3 mL of an acutic anhydride (density : = 168oglm2) 1.080 g/mL = 1.080 mol/ml .. : 102 = 10.59 x16-? mol/ml So, 2.3mL = 24.3578103 mellan So, hectic anhydride is the limiting reagent and it will form 24. 3.57x16 3 mol of acetyl salicylic acid ... .: 24-357x10 mol x 184 g/mol = 4:48 g ③ If the student obtained 4.21 g of aspirin & theo 8 yield = 4.2|| 10: .48 * 33.3 Saxloo : 93.97% she has obtained a little lower yield of may be due to impurity in acetic anhydrider may