SNC4M
Unit 4: Nutritional Science
Lab: Consumer Testing - Which Antacid is the most effective?
Introduction
Titration is an important laboratory procedure used in performing chemical analyses. In
this acid-base titration, an acid is added to a weakly basic antacid tablet; the titration is
stopped when the indicator changes colour, showing that the neutralization reaction is
complete.
Bromothymol blue is a pH indicator for weak acids and bases. It is mostly used in
applications that require measuring substances that would have a relatively neutral pH,
such as managing the pH of pools and fish tanks. In a base it is blue, in an acid it turns yellow,
when in a neutral solution it turns green.
Purpose
In this activity you will test different antacids to see which can neutralize the most
acid. The antacid that neutralizes the most acid per gram can be considered the most effective
Materials
- A weak acid (lemon juice)
- pH indicator (Bromothymol blue)
- A variety of antacid tablets
- Goggles
- mortar and pestle
- 100 mL graduated cylinder
- 250 mL Erlenmeyer flask
- medicine dropper
- balance
- plain white paper
Procedure
1. Record the mass of an antacid tablet.
2. Use a clean pestle to crush an antacid tablet in a clean mortar.
3. Add 50 mL of water to the mortar. Stir to dissolve the tablet, and then pour the contents
of the mortar into a 250 mL flask. Rinse the mortar with another 50 mL of water. Again,
pour the contents into the flask
4. Add 1-2 drops of Bromothymol blue indicator to the flask.
5. Carefully add your acid (the lemon juice), drop by drop – counting the number of drops
you have added, while gently swirling the flask over a sheet of white paper until the
contents of the flask turn green
6. Record the number of drops of acid neutralized by the tablet in the table on the
following page.
7. Repeat steps 1 to 6 for two other brands of antacid.
SNC4M
Unit 4: Nutritional Science
Table 1: _______________________________________________________________________
Tablet 1
Tablet 2
Tablet 3
Brand name
Medicinal ingredients
(include quantities)
Mass of tablet used
Drops of acid required
to neutralize
Calculations:
Determine the effectiveness of each tablet by calculated the amount of acid neutralized per
gram of antacid tablet. Which is the most effective? Which is the least effective?
Follow-up Questions:
1) What materials used in the lab represent an acid, which represent a base?
2) This titration looks at the amount of acid needed to neutralize a base (e.g. to make the
3)
4)
5)
6)
pH around 7). When a person takes an antacid tablet, would the pH of the stomach
raise to 7? Explain your answer.
The Rolaids website claims that their antacid tablets neutralize 47% more acid than
Tums brand. Do your results support this claim?
In addition to heartburn relief, what is a benefit to the body from taking an antacid
tablet (think about the ingredients)
In addition to taking antacids, what are some changes to diet and lifestyle that one
could make to limit heartburn
Explain why heartburn takes place, describing the parts of the digestive system that are
affected.