Introducing students to acids and bases is one of the first lessons that students have in chemistry and you should use it as a springboard to the subject. When teaching about acids and bases, it's important to use clear examples for your terminology and to explain things in the simplest terms possible.
- Skill level:
- Moderately Easy
Things you need
- Acidic or basic substances
- Baking soda
Elicit from children acids and bases that they encounter on a regular basis. This will give you a sense of how much they already do or don't know.
Bring in examples of common acids and bases. For example, baking soda is an easy base to bring in. Oranges with their citric acid, or vinegar are easy bases to bring in.
Demonstrate what happens when you mix baking soda (a base) and vinegar (an acid), together. Ask students why they think the reaction bubbles so much.
Introduce the pH scale to students. Explain that when scientists want to determine how acidic or basic something is they use a scale of 0 to 14.
Draw a diagram on the board. Show that the pH scale really just tells us about the kind of ions a solution releases when it breaks down. Acidic solutions possess lots of hydrogen ions and basic solutions possess lots of hydroxide ions.
Tell children that acidic substances have a pH below 7. Explain that the lower the number is, the more acidic it is.
Ask students what numbers they think very basic substances have on the pH scale. Verify the bases have a pH above seven and that the higher the number, the more basic it is.
Ask students what they think a very neutral number will have on the pH scale. They should guess the number seven. Ask them which substances they think have a pH of seven. Let them guess and then tell them the answer is distilled water.
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