Grade 10 Applied Science – Unit Chemistry - Neutralization
Laboratory – Testing Aspirin
Acetylsalicylic acid is commonly called Aspirin. It was first sold over 100 years ago to relieve pain, and it is
one of the most commonly used drugs in the world. Aspirin has other uses including preventing blood clots.
As its chemical name suggests Aspirin is acidic. This acidity can damage the stomach lining. To lessen this
concern, some Aspirin contain other chemicals that reduce the acidity.
Is the claim true? To measure this, you will use a base to perform a Neutralization Reaction on two types
of Aspirin: (1) regular and (2) acid-reduced. You will use an acid-base indicator called phenolphthalein.
The indicator will show when the reaction is complete. An acidic solution is neutralized when the next drop
of base permanently changes the indicator from colourless to pink.
To explore the idea of neutralization (e.g., action between an acid and a base)
There will be no difference in the reactivity between different types of aspirin.
50 mL graduated cylinder
Two Erlenmeyer flasks
Mortar and pestle
Glass marking pen
40 mL warm water
1 regular Aspirin tablet
1 Extra-strength Asprin
1 reduced-acidity Aspirin tablet
RECALL – NaOH is corrosive. It can cause blindness. Use appropriate lab safety precautions.
Add 20 mL of warm water to each flask
Add five drops of indicator to each flask and swirl gently
Using the mortar and pestle, crush the regular Aspirin tablet into a fine powder. Pour the crushed
tablet into one of the flasks.
Carefully wipe the mortar and pestle with the paper towel to remove any powder.
Using the mortar and pestle, crush the reduced-acidity Aspirin table into a fine powder. Pour the
crushed tablet into the other flask. Repeat for Extra-strength Aspirin
Label the flask “Acid” “Extra-strength Aspirin” and “Reduced-Acidity” with the glass marking pen
Add one drop of NaOH to each flask and record any colour changes.
Continue adding one drop of NaOH to each flask. Record observations after each drop and record
the number of drops of NaOH used
Keep adding NaOH until colour changes stop. NOTE: One liquid may stop before the other liquid.
How many drops of NaOH did it take to turn the regular Aspirin solution pink? Likewise, how many
drops of NaOH did it take to turn the reduced-acidity Aspirin solution pink?
What differences did you observe? Explain any differences.
What factors may contribute to any inaccuracies in your experiment?
How might reduced-acidity Aspirin be the better choice for someone prescribed Aspirin every day?
LAB REPORT: Due ____________________________________