Aspirin Titration

 

Aspirin Titration
Definition of the % w/w aspirin comprehensiveness to acetyl salicylic acid


Introduction: Aspirin is an acid. The active ingredient is acetyl salicylic acid. Titration is a way to determine how much acid is in a solution by adding just enough base of a known concentration to neutralize the acid.  In the titration you will be performing, you will dispense base into a known amount of acid solution to find the unknown concentration. The aspirin will be titrated against a standard solution of base, 0.500 M NaOH. Base will be dispensed from a buret into a beaker containing the dissolved (in ethanol) acid and phenolphthalein indicator, which will show a faint pink color in basic solutions.

Purpose: In this experiment you will run a titration to determine the  aspirin's  comprehensiveness in  acetyl salicylic acid.

Materials:

1. 0.500 M NaOH
2. Ethyl alcohol
3. bayer aspirin
4. 250 mL flask
5. Buret
6. pestle
7. Phenolphthalein indicator
8. Gloves
9. water bottle
10. volumetric cylinder
11. funnel

Procedure:

1. Grind a regular aspirin into a fine powder by using a mortar and pestle.
2. Weigh 0,6 g of the powder with the balance.
3. Place the powdered sample in a 250mL beaker.
4. Add a 20.0 mL portion of ethyl alcohol to the beaker and stir.
5. Add 80.0mL of water to the beaker.
6. Put 4-5 drops of the phenolphthalein indicator in your flask. Put a magnetic stir bar in your flask and place the flask on the center of the stirrer.
7. The buret is filled with 0.500M NaOH. Make sure there are no bubbles apparent in the buret. Record the initial volume on the buret.
8. Begin titrating, Add the NaOH in drops, making note of when the color change occurs. The color should stay stable for 5 min (the  equivalence  is approximately when the solution turned pink from the  phenolphthalein)..
9. Record the final volume on the buret.
10. Fill the tables and make the calculations.

Volume (mL) ΝαΟΗ
Moles NaOH
Mass (g) aspirin
Moles acetyl salicylic acid
Mass (g) acetyl salicylic acid
%  comprehensiveness of aspirin to acetyl salicylic acid