The pH scale is used to compare different substances and identify how acidic or basic they are. A pH of 1 is a strong acid, and a pH of 14 is a strong base. If a substance has a pH of 7, it is said to be neutral (not acidic or basic). In this activity, students will demonstrate their understanding by creating their own version of the pH scale. Students will link together the strength of the acids and bases and their corresponding pH value. They should also include the colors a universal indicator turns when it is mixed in with a substance.
Alternatively, have students complete this assignment after testing different substances in the lab. Students recreate the pH scale choosing the colors they found for the different substances they tested.
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Student Instructions
Create a visual representation of the pH scale.
Engage students by incorporating common household items into your pH lesson.
Collect items such as vinegar, lemon juice, baking soda solution, soap, and tap water. These are safe, familiar, and span a range of pH values.
Help students keep track by labeling cups or beakers with the name of each liquid. This reduces confusion and streamlines the activity.
Ask students to guess whether each liquid is acidic, neutral, or basic. This builds curiosity and encourages critical thinking.
Let students add universal indicator drops to each liquid and observe the color change. Compare results to the pH color chart together.
Lead a discussion on why certain household items are acidic or basic, and how this relates to their everyday uses. Connect science to students' lives!
The pH scale is a tool for measuring how acidic or basic a substance is, ranging from 1 (strong acid) to 14 (strong base), with 7 being neutral. In middle school science, students use it to classify substances and understand chemical properties.
Students can create a visual pH scale by coloring boxes to show how a universal indicator changes color at each pH value and including pictures of common substances that fit each pH range.
A universal indicator turns red for strong acids (low pH), green for neutral (pH 7), and blue to purple for strong bases (high pH). The colors help identify a substance’s acidity or basicity.
Examples include lemon juice (acidic, pH ~2), water (neutral, pH 7), and baking soda (basic, pH ~9). These help students connect the pH scale to real-life items.
Acids have low pH (1–6), bases have high pH (8–14), and neutral substances have a pH of 7. Acids taste sour, bases feel slippery, and neutral substances are neither acidic nor basic.