SNC2P
Testing the Effectiveness of Antacid Tablets
Name:
The main ingredient of stomach juice is hydrochloric acid. If
concentrations of the acid in the stomach are too high, problems can
occur – pain, swelling, inflammation, bleeding in the stomach lining.
One solution is to take a medication that contains an antacid to try
and neutralize the acid in the stomach.
Advertisements for antacids often make claims about the tablet’s
ability to ‘consume’ excess stomach acid. How valid are these
claims? A typical pharmacy may offer dozens of different antacids to
chose from. Which one do you chose? In this investigation you will
perform tests to find out.
Problem
Which over the counter antacid is most effective in neutralizing acid?
Internet Search
1. What is heartburn?
2. What is acid reflux?
3. What is an antacid tablet?
4. Watch the Tums commercial and the Rolaids commercial on
Youtube. What did you learn from the commercials? What did
each tablet claim?
SNC2P
Testing the Effectiveness of Antacid Tablets
Antacid Tablet Information
Table 1: Active Ingredients
Antacid Table Available
Tums Extra Strength
Rolaids Extra Strength
Kirkland (Costco) Antacid
Tablet
Equate (Walmart) Antacid
Tablet
Name:
Active Ingredient in Each Tablet
750 mg Calcium Carbonate
675 mg Calcium Carbonate
135 mg Magnesium Hydroxide
500 mg Calcium Carbonate
675 mg Calcium Carbonate
135 mg Magnesium Hydroxide
Chemistry Background
Calcium Carbonate
 What is the formula?
 Write the equation for Calcium Carbonate and H Cl  Calcium
Chloride and carbon dioxide and water. (get teacher approval)
Magnesium Hydroxide
 What is the formula?
 Write the equation for Magnesium Hydroxide and H Cl 
Magnesium Chloride and water. (get teacher approval)
SNC2P
Testing the Effectiveness of Antacid Tablets
Name:
Materials
 Hydrochloric acid
 Sodium hydroxide
 Methyl orange indicator (turns from red to yellow at pH of 3)
 2 brands of antacid tablets
Apparatus
 250 mL Erlenmeyer flask
 100 mL graduated cylinder
 Triple beam balance
 Mortar and pestle
 A ring stand with a clamp
 A buret
Safety!
 Wear safety goggles
 Handle acids and bases
carefully
 Flush with water for 15
minutes if acids or bases come
in contact with skin or eyes.
Tell Teacher.
Procedure
o Obtain one antacid tablet. Find its mass using the triple beam
balance.
o Crush the tablet using the mortar and pestle.
o Carefully pour the crushed tablet into the 250 mL Erlenmeyer
flask.
o Measure 50 mL HCl in the graduated cylinder
and carefully add to the Erlenmeyer flask.
Swirl carefully to mix the tablet and acid.
o Add 5 drops of the methyl orange to the flask.
The solution will turn a reddish colour.
o Set up the ring stand with the burette securely in the clamp.
SNC2P
Testing the Effectiveness of Antacid Tablets
Name:
o Ask teacher to fill the burette with sodium hydroxide. Record
the starting level.
o Slowly add sodium hydroxide to the Erlenmeyer flask. Swirl
every few mL.
o Stop adding sodium hydroxide when the reddish colour turns to
yellow. Record this end volume.
o Clean all of your equipment. Dry equipment. Repeat these
steps using the other antacid tablet.
Observations and Data
Tums NaOH start:
Tums NaOH finish:
Rolaids NaOH start:
Rolaids NaOH finish:
Table 2: Antacid neutralizing HCl data
Antacid
Mass of Antacid Volume of HCl
(g)
(mL)
Volume of NaOH
added (mL)
Tums Extra
Rolaids Extra
Calculations
Volume of HCl neutralized = Volume of HCl – Volume of NaOH
Tums
Rolaids
Neutralizing Ability = Volume of HCl neutralized ÷ Mass of tablet
Tums
Rolaids
SNC2P
Testing the Effectiveness of Antacid Tablets
Table 3: Summary of Calculations
Antacid
Volume of HCl Mass of Antacid
neutralized
(g)
(mL)
Tums Extra
Name:
Neutralizing
Ability of
Antacid (mL/g)
Rolaids Extra
Analysis
1. Why is it important to frequently swirl the mixture?
2. What made the indicator change from red to yellow?
3. Now that you have worked through the procedure a couple of
times, do you think there were any errors made that would
affect your date? What improvements would you make if you
had to redo the lab?
4. Given your results, which antacid tablet would you consider
taking if you had a stomach problem? Elaborate your answer by
explaining why you chose this tablet.
5. You investigated only solid antacids. Liquid antacids also exist.
Do you think they would be more or less effective at
neutralizing acid? Explain why you think that.
6. Do you think liquid antacids would be faster or slower at
neutralizing acid in your stomach? Explain why you think that.