BioLab 26 - Effectiveness of Antacids
Introduction:   In this investigation, you will mix an antacid tablet with water and an indicator. The indicator changes color depending on whether an acid or a base is present. Then you will determine how much acid can be neutralized by the antacid tablet.
Materials: 100 ml beaker, graduated cylinder, 250 ml flask, medicine dropper, distilled water, antacid tablet, 50 ml 1 M hydrochloric acid, acid/base indicator
Procedure:
  1. Obtain an antacid tablet. Record the brand name and active ingredient(s) listed on the label.
  2. Put 100 ml of distilled water in a flask. Dissolve the tablet in the water. (Some tablets may not dissolve completely.)
  3. Put a sheet of white paper under the flask. Add about 5 drops of indicator to the solution.
  4. Add 50 ml of 1 M hydrochloric acid in a beaker.
  5. Use a medicine dropper to add the 1 M hydrochloric acid to the flask. NOTE; in science, a medicine dropper is a transfer pipette. Always hold it straight up and down, never at an angle. This lets gravity take the drop off the dropper, and makes each drop the same volume. Add five drops at a time, then swirl the contents of the flask.
  6. Keep track of the number of drops of 1 M hydrochloric acid added to the flask. At some point, adding drops of hydrochloric acid will cause swirls of color to form in the solution. This means the antacid tablet can neutralize only a little more acid. At that point, add only one drop of acid at a time. Swirl the flask after each drop.
  7. Stop adding acid when the color change does not fade. At this point, the antacid tablet cannot neutralize any more acid.
  8. Record the number of drops of acid used.
  9. Repeat steps 1 through 8 with different brands of antacid.
DATA TABLE
Brand of Antacid Active Ingredient(s) Drops of Hydrochloric Acid Added
     
     
     

Conclusion:
1. What active ingredients are in the brands tested?
 
2. Do some antacids contain inactive ingredients? If so, what are they?
 
3. Which antacid tablet neutralized the most acid? What active ingredient(s) does it contain?
 
4. Which antacid tablet neutralized the least acid? What active ingredient(s) does it contain?
 
5. What factors could account for any differences you observed in the acid-neutralizing capacities of the antacids tested?