Physical Science
Ch. 23: Acids, Bases & Salts
Name: ____________________________ SN: ______
Antacids Lab
Problem:
Which antacid is the most effective for neutralizing stomach acid?
Research:
We use acids and bases every day of our lives! In fact, we would be unable to survive without acids and
bases. For example, in order to digest our food the cells lining our stomach secrete gastric juices that
have a pH between 1.5 and 3.5. Luckily our stomachs are designed to handle these acidic conditions!
Our esophagus is not however! Sometimes stomach acid is able to splash up into our esophagus which
causes the uncomfortable feeling of heartburn. Many people take products called antacids to help
relieve their symptoms. Antacids are bases so when they come in contact with the stomach acid, a
neutralization reaction takes place!
In today’s experiment, we will be using Coca Cola as our acid because it has a pH of approximately 2.5
which is similar to the pH of “stomach acid.”
Hypothesis:
Which antacid do you think will work the best? Why?
Experiment:
1. Pour _________ mL of Coca Cola into a plastic cup.
2. Use the pH paper at your station to find the pH of your Coca Cola. Record your pH value in the
Coca Cola column of the data table. Discard your pH paper in the garbage can.
3. Prepare your antacid.
a. If you are testing a solid, follow the suggested dosage on the container to determine
how much you will need. Then grind it into a fine powder by crushing it with a mortar
and pestle.
b. If you are testing a liquid, you need to measure out the correct amount using the
measuring device included.
4. Pour your sample carefully into the Coke.
5. Stir the mixture with a stirring rod for at least 30 seconds to make sure that the antacid is
dissolved.
a. If it is not dissolved after 30 seconds, continue stirring until it is all dissolved.
6. Take the pH of the Coke/antacid mixture using a new piece of pH paper and record your findings
on your data table. Discard your pH paper in the garbage can.
7. Clean and dry all of your lab equipment. Throw away any garbage.
8. Send one person up front to record your data on the front board.
9. Have your teacher initial here before leaving your lab station: __________
Antacid Lab Data Table
Class
Initial pH of
Coca Cola
pH with
Antacid 1
pH with
Antacid 2
pH with
Antacid 3
pH with
Antacid 4
pH with
Antacid 5
pH with
Antacid 6
__________
__________
__________
__________
__________
__________
2nd hour
3rd hour
4th hour
6th hour
7th hour
Average
pH
Analysis:
1. Which antacid(s) would be least effective in neutralizing stomach acid? Explain your choice
using data from the lab.
2. Did you notice a difference in the neutralization abilities between the generic tablets and the
name-brand tablets? Explain your choice using data from the lab.
3. Did you notice a difference in the neutralization abilities between liquid antacid and solid
antacid? Explain your choice using data from the lab.
4. In your opinion, what are some of the limitations of measuring pH with pH paper?
Conclusion:
On a separate sheet of paper, write a conclusion paragraph based on your findings. You should write
neatly and use complete sentences. Your conclusion should discuss the following:
Did your data support or reject your hypothesis? Explain why or why not.
What evidence (data, observations, etc…) did you use to come to this conclusion?
What would you do differently if you repeated this experiment?
Where would you go from here (what would you test next)?