The purpose of this Titration Analysis of ASA experiment was to use titration analysis techniques to determine the amount of ASA content contained of a standard pain-relief tablet.

Pre-lab Calculation:

• Mass Of KHP required to prepare 100.0mL of a 0.150 mol/L solution is:

Post-lab Calculations:

• Part 1: Standardization of sodium hydroxide solution(NaOH(aq)) Calculations

In order to calculate the concentration of NaOH(aq), we must first find the concentration of KHP.

• Uncertainties Used For Calculations:

• Volumetric Flask: ±0.8ml used for preparing the standard solution.

• Electronic Mass Scale: ±0.01g used in measuring the amount of KHP needed.

• Percent Uncertainty for the concentration of KHP: 0.33% + 0.08% = 0.41%
• Concentration of KHP:

 (aq) ±0.41%

The concentration of KHP（aq）is now calculated with a value

 of 0.149mol/L with an uncertainty of 41%. In order to calculate the concentration of NaOH(aq), the calculation of the average volume of NaOH(aq) added to KHP in the 4 trials are needed:

• We will not round any values until the very end

• On Average,  of NaOH(aq) are added to KHP(aq)

Since we have acquired the data about the average amount of NaOH (aq) are added to KHP(aq) , it is now possible for us to calculate the concentration of NaOH(aq) using molar ratio, but before we go any further, we need to sort out our uncertainties clearly!

• Uncertainties Used For Calculations:

• Concentration of KHP:  (aq) ±0.41%
• Pipet: 0.04ml used for pipetting 10ml of KHP solution.

• Burette(The uncertainty not specified on this instrument): 0.10mL Initial reading and final reading to the nearest 0.1mL, since we took 2 measurements to the nearest 0.1mL, the calculation for this uncertainty is 0.05mL2 = 0.10mL

• Final Uncertainty for the concentration of NaOH(aq): 1.03%+0.40% = 1.43%

• Concentration Of NaOH(aq):

 1.43%

• Part 2: Titration of ASA tablet with sodium hydroxide(NaOH(aq)) Calculations

• Unknown Variable(s):

• 325mg of ASA/Tablet
• Concentration of KHP(aq): 0.149mol/L KHP(aq) ±0.41%
• Average NaOH(aq) added to dissolved ASA solution:

• Uncertainties Used For Calculations:

• Concentration of NaOH(aq): 1.43%
• Burette(the uncertainties were not specified on this instrument): 0.10mL Initial reading and final reading to the nearest 0.1mL, since we took 2 measurements to the nearest 0.1mL, the calculation for this uncertainty is 0.05mL2 = 0.10mL

*Note: ASA (C9H8O4 (aq))’s state is aqueous because we have crushed the ASA(s) and dissolved it in boiling water)

- Final Percent Uncertainty for mass of ASA: 1.43%+1.03%=2.46%

( 361.1916mg

=361.19mg (2.46%)

• Percent Differential from Accepted Result (325mg):
• (361.19 – 325.0)/325 x 100 = 11.13538462%

=11.08%

• Converted Result:

=

• Final Result + Uncertainty: 361.1916mg11.08% or 361.19mg

End of Data and Processing Section of this lab report, please see next page for the Conclusion and Evaluation of results for this lab.

Conclusion & Evaluation:

The purpose of this “Titration Analysis of ASA” experiment was to use titration analysis techniques to determine the amount of ASA content contained of a standard pain-relief tablet. According to the product label, the mass of ASA in a standard pain-relief tablet is 325mg, however based on the calculations in my data collection, this result differentiates from my calculation of 361.1916mg of ASA in a standard pain-relief tablet by a factor of approximately +11.08% or +. My end result from this experiment suggested that there is 11.08% more ASA in a standard pain-relief tablet than the accepted value on the label, though my end result maybe miles off, but I am here to evaluate my experimental process and what could have caused such a great difference.

Although I have performed this experiment with the precision and accuracy, an end result off by +11.08% from the accepted value was more than I anticipated. There are a few experimental flaws that could have seriously affected our end results of the experiment. One being that the ASA pill was not 100% dissolved in the hot water; it has continuously left cloudy substances and little solid portions of the ASA pills at the bottom of the flask, this was a major factor in the 11.08% end result difference because the ASA solutions were not completely reacted in the correct ratio. Another factor that could have affected our result was the ratio of water vs. the drops of phenolphthalein indicator added to the ASA solution, although water did not play a role in the reaction because it did not react with the standard solution, it did affect the concentration of the phenolphthalein indicator, too much water may have diluted the indicator, and therefore affect our judgment at the endpoint on whether if the chemical occurred. Perhaps one of the most significant flaws is the human errors that occurred during the experiment; extracting solution using the pipette can be very inaccurate because it is very difficult control the 10ml of solution that gets extracted into the pipette using the pressure bulb, the pipette could also have contained left over solutions from the previous trials, and because we have extracted the solutions this 3 times, the pipette could have had a serious effect on our results making it significantly less accurate.

Aside from the flaws, there are some areas in this experiment that we could have done better. We could have crushed the pills first and then dissolve them in the hot water; I think this method could have resulted a more accurate end result to the experiment if we manage to not lose any crushed powder because the powder would have dissolved much better than the solid pills. The second improvement is that we could have the used less water or more phenolphthalein indicator, since water does not play a part of the reaction process, less water used could have made it for us to identify the change in the color of the solution easier. For the pipette error factor could have been prevent with better equipment, the students in our group found it very difficult to control the pressure of the bulb without losing some solution, I didn’t think the pipette with the pressure bulb was the best equipment for accuracy, other pipettes with better methods of solution extraction methods could have been used and improve our final results from differentiating from the accepted value.

This experiment was quite challenging because it required many accurate measurements of solutions and excellent observation skills from everyone to record the endpoint of the reaction.