The Difference Between Acids and Bases Using Different Indicators
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Lejon Ross Betsy Ross Elementary School
6059 South Wabash
Chicago IL 60637
This mini-teach is designed for the upper grade level; namely the seventh
and eight grades.
1. To identify and distinguish acids and bases.
2. To identify the differences between acids and bases using litmus paper,
pH paper and indicator solution.
Isopropyl alcohol (rubbing alcohol)
AT FOUR WORKSTATIONS:
Cups Baking Soda
droppers (10) Distilled Water
Red or Blue Litmus paper Bathroom Cleaner
pH paper Small clear jars (12)
Tap Water Lemon juice
Liquid detergent Ammonia
Acetone (finger polish remover)
Making Indicator Solution
1. Obtain a clean bowl and add one pint of blueberries.
2. Add one bottle of rubbing alcohol and let stand for 24 hours.
3. After 24 hours, drain solution into another clean container.
1. Test tap water, lemon juice, vinegar, sprite and liquid detergent with
red or blue litmus paper (have students record results).
Ask questions such as:
a. What color does litmus paper turn when it is a base? (blue)
b. What color does litmus paper turn when it is a acid? (red)
c. What are acids? (All acids contain hydrogen and they burn)
d. What are bases? (Bases contain negatively charged ions called
hydroxide ions. They are slippery to touch.)
2. Test tap water, lemon juice, vinegar, sprite and liquid detergent with
pH paper (have students record number of reading)
a. With pH paper, how can you figure out what is an acid or a base?
(Acids have a pH below 7, Bases have a pH above 7 and distilled
water has a reading of 7 because it is neutral.)
Testing with indicator
1. Add 5 drops of tap water to a clear jar.
2. Add 5 drops of indicator solution to the jar also.
3. Swirl solution around and record results.
4. Repeat steps 1 through 3 with lemon juice, vinegar, sprite and liquid
5. Try this same procedure with ammonia, acetone, baking soda solution (baking
soda and water) and bathroom cleaner and label them unknown A through E and
let the students figure out which one's are acids and which one's are bases.
Acids turns red and pink in the indicator solution. Bases turns green in the
The students will be able to determine on their own how to classify acids and
bases using litmus paper, pH paper and indicator solution. Students will be
asked questions throughout the experiment to assess what is being learned.
Hann, Judith. How Science Works. Pleasantville, New York, Reader's
Digest Association, Inc., 1991.
VanCleave's, Janice. Chemistry for Every Kid. New York, John Wiley
& Sons, Inc., 1989.