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.
- 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
- 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.
- Rinse the eyedropper thoroughly.
- Add ten drops of lemon juice (an acid) to each test tube.
- Label each test tube with the name of one of the liquid antacids you are testing.
- 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.
- In a table such as the one below, record the number of drops needed to neutralize the acid.
- Repeat this process with the remaining types of antacids, adding drops of one antacid to each of the remaining test tubes.
- 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.