Baking Soda Bubbles and the Science of Sour

In this family STEM activity, students use baking soda to help detect the presence of acids in foods and explore the relationship between acidity and whether or not a food tastes sour.

A Simple Test for Sour

When you eat or drink something, your taste buds detect qualities like sour, sweet, and bitter. If you drink pickle juice, you might immediately describe it as sour. The same would be true for lemon juice. But a food or drink that also contains ingredients that counter (or mask) the "sour" may or may not taste particularly sour when you eat or drink it.

Things taste sour to us because of their acidity. One way to measure the acidity of a food or drink is to test its pH level. This week's family science activity demonstrates another way for students to determine whether or not a food is acidic by doing a simple test with baking soda and observing the reaction that happens when the food or drink is combined with baking soda. When baking soda and an acid are mixed, carbon dioxide gas is released. By observing and comparing differences in this chemical reaction between foods and drinks, students can determine which foods are likely to be sour.

If a food is acidic, what will you see when it mixes with baking soda? Will you be able to see a clear difference beween highly acidic foods, foods that are slightly acidic, foods that are neutral, and foods that are basic? Find out with this bubbly kitchen chemistry experiment!

The following Science Buddies activity on the Scientific American website has all the information you need to do this science activity with your students at home or in class: A Simple Sourness Detector.

Making Connections

Students interested in science questions related to this week's family science activity and other kitchen chemistry and tastebud-focused science experiments, may also enjoy the following hands-on science project ideas:

• Do You Have the Willpower to Taste Something Sour?
• Taste Bud Science
• Taste Test: Do You have the Papillae of a Supertaster?
• The Science of Too Sour
• Sniffing Out the Science of Smell
• Sweet and Sour Tasty Kitchen Science

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