Experimental General Chemistry 1
Experiment 12: Analysis of a Commercial Aspirin or ASA Tablet
Laboratory Data Sheet
Name:
Section:
Brand name of commercial tablet:
Calculations.
1. Standard solutions and Beer’s law calibration curve
(1) Mass of SA = ______ g
Molar mass of salicylic acid (SA), HOC6H4COOH = ______ g/mol
(2) Moles SA = mass/molar mass = ______ mol SA
The SA is hydrolyzed and quantitatively transferred to a 100 mL volumetric flask, so:
(3) Concentration of SA stock solution = mol/0.100L = (2)/0.100 = ______ mol/L
(4) Concentration of SA solution “5” (0.5 mL stock to 10 mL)
= (0.5/10)x(stock solution concentration) = ______ mol/L A5= ______
SA solution “4” (0.4 mL stock to 10 mL) = ______ mol/L A4= ______
SA solution “3” (0.3 mL stock to 10 mL) = ______ mol/L A3= ______
SA solution “2” (0.2 mL stock to 10 mL) = ______ mol/L A2= ______
SA solution “1” (0.1 mL stock to 10 mL) = ______ mol/L A1= ______
Enter these concentrations and absorbance in an Excel sheet and create a calibration curve. Attach this calibration curve with this report.
2. Analysis of unknown Aspirin tablet
Note that now your initial mass is the mass of the aspirin (or ASA) tablet, which is not pure salicylic acid!
(1) Mass of tablet = ______ g Aspirin
(2) Absorbance of “ASA UNKNOWN” = ______
(3) Concentration of ASA in unknown diluted solution as determined from the calibration curve,
CASA, unknown = ______ mol/L
(4) Concentration of “ASA UNKNOWN”: prepared by dilution 0.3 mL to 10 mL, so the concentration in the “STOCK UNKNOWN” was 10/0.3, therefore