2. How does your experimental value of the mass acetylsalicylic acid in the tablet compare to the
mass of Aspirin in the tablet (printed on the label of the bottle)? Calculate the percent error. Do
you think this is a reliable method for determining the amount of aspirin in a tablet?
The experimental value of the mass of acetylsalicylic acid in the tablet is less than the mass in
the tablet.
Percent Error=
((
|Accepted-Experimental|)/(Accepted))x100%
Percent Error=((
|500mg-378|)/(500))x100%
Percent Error=24.4%
The percent error is 24.4%, which leads to the conclusion that this may not be a reliable method
for determining the amount of aspirin in the tablet.
3. List three possible experimental errors that may have caused deviation from the accepted
value.
One experimental error could be that the Aspirin tablet did not fully dissolve into solution. This
would have caused a lack of acetylsalicylic acid in the filtrate, making the concentration lower
than expected. Another experimental error could have been the evaporation of acetylsalicylic
acid during heating. This would also cause the acetylsalicylic acid concentration to be lower than
expected. An additional source of error could have been incorrect placement of the cuvette in the
colorimeter. This may have caused the absorbance to be lower that the actual absorbance.
4. Some colorimeters measure percentage transmittance (%T) only. If a solution has a %T of
73.5%, then what is the value of the absorbance? If a solution has an absorbance of 0.333, then
what is the value of the %T? Show your calculations clearly.
A=2-log(%T)
A=2-log(73.5)
A=0.134
If a solution has %T of 73.5%, the absorbance would be 0.134.
A=2-log(%T)
0.333=2-log(%T)
-1.667=-log(%T)
1.667=log(%T)
10
1.667
=%T

46.5=%T
If a solution has an absorbance value of 0.333, then the %T would be 46.5%.