How to Test the pH of Everyday Liquids with Kids

Turn your kitchen into a science lab by testing the pH of common household liquids with simple materials and safe methods.

1. Gather Your pH Testing Materials. The easiest method uses pH test strips, available at pool supply stores, pharmacies, or online for about $5-10. These color-coded strips show pH levels from 0 (very acidic) to 14 (very basic), with 7 being neutral. For a homemade alternative, create red cabbage indicator by chopping half a red cabbage, boiling it in water for 10-15 minutes, then straining the purple liquid. This natural indicator changes color: red/pink for acidic solutions, blue/green for basic ones, and purple for neutral. You'll also need small clear containers (shot glasses or small bowls work well), labels, and a notebook for recording results. Gather liquids from around your home: lemon juice, vinegar, baking soda mixed with water, milk, coffee, soap solution, and plain water.
2. Set Up Your Testing Station. Choose a well-lit area, preferably near a sink for easy cleanup. Lay out your containers and label each with the liquid you'll test. Pour small amounts—just enough to dip a test strip or add a few drops of cabbage indicator. Create a simple chart with columns for the liquid name, predicted pH (acidic, neutral, or basic), actual pH reading, and observations. This helps kids practice scientific method skills like forming hypotheses and recording data. Remind children that this is observation only—no tasting any of the test liquids, even familiar ones like milk, since they've been sitting out and may have additives.
3. Test and Record Your Results. If using pH strips, dip each strip into a different liquid for the time specified on the package (usually 1-2 seconds), then compare the color to the chart provided. Record the number. With cabbage indicator, add 2-3 drops to each liquid and watch for color changes. Acidic solutions turn the indicator red or pink, basic solutions turn it blue or green, and neutral solutions stay purple. Encourage kids to make observations beyond just the pH reading: Does the liquid fizz? Change color dramatically? Smell different? These details help reinforce that chemistry involves multiple types of changes. Common results to expect: lemon juice and vinegar will be very acidic (pH 2-3), baking soda solution will be basic (pH 8-9), and milk will be slightly acidic (pH 6-7).
4. Explore Patterns and Extensions. Once you have results, look for patterns together. Many cleaning products are basic, while foods like citrus and coffee tend to be acidic. Discuss why this might matter—acidic foods can affect tooth enamel, while basic cleaners help break down grease. Try mixing an acidic liquid with a basic one and test the result. What happens to the pH when you combine lemon juice with baking soda water? This introduces the concept of neutralization reactions. For older kids, extend the experiment by testing the same liquid at different temperatures, or testing how adding sugar or salt affects pH. You might also test natural water sources if you have access to pond, well, or rainwater (though don't drink any untreated water).