How to Test the pH of Everyday Liquids with Your Kids

Learn to safely test the pH of household liquids using simple materials for an engaging science experiment with children of all ages.

1. What You'll Need. Gather pH test strips (available at pool supply stores, pharmacies, or online), small clear containers or cups, measuring spoons, a notebook for recording results, and the liquids you want to test. Safe household liquids to try include lemon juice, baking soda mixed with water, milk, coffee, soap mixed with water, and plain tap water. You'll also want paper towels for cleanup and a permanent marker to label your containers.
2. Safety First. Only test liquids that are safe to handle and won't harm skin. Avoid cleaning products, bleach, or any chemicals not meant for consumption. Always supervise young children during the experiment. If testing hot liquids like coffee, let them cool to room temperature first. Wash hands thoroughly before and after the experiment, and never put used pH strips back into the container.
3. Setting Up Your Test. Pour about 2 tablespoons of each liquid into separate, labeled containers. For powdered substances like baking soda, mix 1 teaspoon with 3 tablespoons of water. Line up your containers and have your notebook ready to record results. Create a simple chart with columns for the liquid name, pH number, and whether it's acidic (below 7), neutral (7), or basic (above 7).
4. Testing the pH. Remove one pH strip from the container, being careful not to touch the colored indicator pads. Dip the strip about half an inch into the first liquid for 1-2 seconds, then remove it immediately. Wait 15-30 seconds for the colors to develop fully. Compare the colors on the strip to the color chart that came with your pH strips. Record the pH number in your notebook. Use a fresh strip for each liquid to avoid contamination.
5. Understanding Your Results. The pH scale runs from 0 to 14, with 7 being neutral (pure water). Numbers below 7 are acidic - the lower the number, the more acidic. Numbers above 7 are basic or alkaline - the higher the number, the more basic. Help kids understand that lemon juice and coffee are typically acidic (pH 2-5), while baking soda water and soap are basic (pH 8-11). Most drinking water is close to neutral.
6. Exploring Further. Try testing the same liquid at different temperatures or concentrations. Mix lemon juice with baking soda and test the pH before and after the reaction. Test different brands of the same type of liquid to see if pH varies. Create colorful charts or graphs to display your findings. You can also research why certain liquids are acidic or basic and discuss how pH affects taste, cleaning power, or plant growth.