Antacid Potentcy

3.9 based on 290 ratings

Updated on Feb 05, 2012

Grade Level: 7th – 10th; Type: Chemistry


When an acid and a base combine, the base neutralizes the acid in a chemical reaction. This is how antacids work as well. This project will test which antacids are most potent in neutralizing lemon juice.

Research Questions:

  • How do antacids work?
  • Which antacid is most potent?

Have you ever had heartburn? If so, you may have used an antacid to soothe your upset stomach. An antacid is essentially a base that neutralizes your stomach acid. In this project, you can test out which antacid is most potent – at least on the acid in lemon juice!


  • Grape juice (no sugar added)
  • Eye dropper
  • Lemon juice
  • Several test tubes
  • Several different types of liquid antacids

Experimental Procedure

  1. Add ten drops of grape juice to each test tube. Grape juice is a natural acid-base indicator, so it turns colors depending on whether the solution it is placed in is acidic or basic.
  2. Rinse the eyedropper thoroughly.
  3. Add ten drops of lemon juice (an acid) to each test tube.
  4. Label each test tube with the name of one of the liquid antacids you are testing.
  5. Add the first antacid, drop by drop, to the first test tube. Stop as soon as the solution changes colors. A color change means that the antacid has neutralized the acid in the lemon juice.
  6. In a table such as the one below, record the number of drops needed to neutralize the acid.
  7. Repeat this process with the remaining types of antacids, adding drops of one antacid to each of the remaining test tubes.
  8. Record your data. Which antacid neutralized the acid most quickly? What does that tell you about that antacid?

Terms/Concepts: Acids and bases; Neutralization; What causes upset stomach?

References: Easy Genius Science Projects with Chemistry, by Robert Gardener, pp. 46-47.

Keren Perles has worked as an educational writer, editor, teacher, and tutor of all ages. Her experience spans the subject areas, from science and math, to English and the Hebrew language.

How likely are you to recommend to your friends and colleagues?

Not at all likely
Extremely likely