Determination of Aspirin Lab Write-up - Determination of...

Determination of Aspirin in Tablets
Chemistry 112L, Section 001
September 17, 2014
A. Research Question
What is the relationship between the concentration of aspirin and the absorbency of the
solution?
B. Observations & Results
Tables
Table 1. Molar Absorptivity of Aspirin: Concentration vs. Absorbance
Aspirin (g/mL) Absorbance (au)
0.00 g/mL 0.000 au
0.0000100 g/mL 0.129 au
0.0000200 g/mL 0.219 au
0.0000400 g/mL 0.361 au
0.0000600 g/mL 0.513 au
0.0000800 g/mL 0.773 au
0.000100 g/mL 1.169 au
Table 2. Aspirin Tablet Data
Brand Advertised
% aspirin
(from bottle)
Tablet
mass (g)
Abs of analyzed
tablet solution
Mass of
aspirin per
tablet (g)
% aspirin
per tablet
(from
analysis)
Bayer 82.9 % 0.392 g 0.806 au 0.177 g 45.2 %
Kroger 86.7 % 0.375 g 0.368 au 0.388 g 103%
Graphs

0 0 0 0 0 0 0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
f(x) = 10390.39x
R² = 0.99
Molar Absorptivity of Aspirin: Absorbance vs. Concentration
Concentration (g/mL)
Absorbance (au)
Calculations
Aspirin concentration calculations are written on the attached notebook paper.
Advertised % of aspirin per tablet:
Bayer: 0.325 g / 0.392 g = 0.829 0816… = 0.829 *100 = 82.9 % aspirin by mass
Kroger: 0.325 g / 0.375 g = 0.866 6666… = 0.867 * 100 = 86.7 % aspirin by mass
Mass of aspirin per tablet, and percent of aspirin per tablet are calculated in the analysis.