How to Determine Acids & Bases

Find the acidity of a solution with a pH strip.

The acidity of a solution is based on the concentration of hydrogen ions and are detectable using a pH scale. If the pH level is less than 7, the solution is acidic while a level greater than 7 represents a basic solution. By using a pH strip and a color-coded pH chart, you can determine if a solution is more acidic or basic depending on the color change.

Things You'll Need

• pH strip
• Beaker
• Liquid solution

Instructions

1. Purchase a pack of pH strips from your local pet store in the aquarium accessories department or a retailer that sells science equipment.

2. Pour the solution into a scientific beaker and submerse half the paper strip into the product sample for about two or three seconds or until you see a change in color.

3. Compare the color of the pH strip with the scale provided by the manufacturers of the pH strips. If the strip turns a dark red or an orange color, the solution is an acid. If the color turns dark blue or a bluish tint, the product is a base.

4. Quantify your color on the pH scale. Use the scale on the bottom of the Vision Learning website (see resources) to put a value on your pH color. If the color did not change, it is considered neutral and quantified by 7. For pH levels that are 0 to 6, the solutions are considered acids while pH levels of 8 to 14 are considered bases.

References

• Stephen K. Lower: Introduction to Acid-Base Chemistry

Resources

• Vision Learning: Acids and Bases