Lesson Plan: Acids, Bases and Neutrals
This lesson will teach students about the pH scale and how to differentiate between acids, bases and neutrals.
Materials needed: pH paper, bottled water, water from the drinking fountain, lemon juice, apple juice, egg whites, milk, paper towels, goggles small plastic cups.
Prior to beginning this lesson, review safety rules for scientific investigations.
• Introduce the following vocabulary words: acid, base, neutral, pH, pH scale.
• Ask students to tell what they know about acid, bases and neutrals and how to differentiate between them. Have students fill out the “K” and “W” sections of a K-W-L chart.
• Explain that an acid is a substance whose pH is less than 7; a base is a substance whose pH is 7 or above; a substance that is a base is also considered to be alkaline; a substance with a pH of 7 is considered neutral. Write <7=acid; 7=neutral; >7=base on the chalkboard. Tell students pH paper can be used to determine whether a substance is an acid, a base or neutral.
• Divide students into groups. Direct each group to select a tester to dip pH paper into each substance and a recorder to write down the group’s observations. The remaining members of each group would observe and note what was observed.
• Give each group member goggles and gloves to wear during testing and observation. Give each group pH paper and small plastic cups containing bottled water, water from the drinking fountain, apple juice, milk, egg whites and lemon juice.
• Have each group conduct testing and discuss their findings.
• Have each group report their findings. Record findings on the chalkboard or chart paper. Ask students if they are surprised by the findings. Discuss the findings. Complete the “L” section of the K-W-L chart.
• Have students write a reflection about what they have learned in their science journals.
