Question

Please help me answer questions from pre-lab homework

Aspirin Analysis Lab

1) Calculate the molar concentration (molarity) of a 250 mL stock solution prepared from 0.5 g of pure acetylsalicylic acid. 2) Calculate the molar concentration (molarity) of a 50 mL solution prepared from 2.5 mL of the acetylsalicylic acid stock solution from question 1. This will be labeled as Standard Solution A. 3) Simlarly, calculate the molar concentrations (molarities) of 50 mL the four individual solutions prepared from 2, 1.5, 1, and 0.5 mL, respectively, of the acetylsalicylic acid stock solution from question 1. These will be labeled as Standard Solutions B, C, D E, respectively 4) Transfer the values of molar concentrations obtained into the following table. The absorbance values obtained for the solutions A-E are included Solution Molar Concentration Absorbance 0.4846 0.3794 0.2690 0.1913 0.0996 By hand or using Excel, build a standard calibration curve and find the equation of this curve 5) Briefly explain the purpose of building a standard calibration curve 6) A spectrophotometric analysis of 0.2223 g aspirin product was performed using the procedure above (Part Ill on page 3). The absorbance of the unknown sample solution of this product was determined to be 0.3574 Use the equation of the standard calibration curve from question 4 and back calculate the amount of pure acetylsalicylic acid present in this aspirin product. a. b. Find the % purity of the aspirin product