Name: _____________________________________
Section: __________________________________
Acids and Bases Investigation Using Phenolphthalein
Grade Level: Science 7
Objective: Identify whether common household substances are acidic, basic, or neutral
using phenolphthalein solution as an indicator.
Materials:
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Phenolphthalein solution (indicator)
Dropper
Small transparent containers (for
testing)
Substances to test:
- Vinegar
- Sugar solution
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- Salt solution
- Shampoo
- Cooking oil
- Liquid dishwashing soap
- Water
- Alcohol
Activity Table: Observation and Inference
� Reminder: Phenolphthalein turns PINK IN BASIC SOLUTIONS and remains COLORLESS IN
ACIDIC OR NEUTRAL SOLUTIONS.
Substance
Vinegar
Sugar solution
Salt solution
Shampoo
Cooking oil
Liquid dishwashing
Water
Alcohol
Observation after adding
phenolphthalein
Inference (Acid, Base,
Neutral)
Guide Questions:
1. What does a color change (to pink) indicate about a substance?
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2. Which of the tested substances are likely to be acids? What is your basis?
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3. Which substances are likely to be bases? How can you tell?
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4. Why is it important to test substances before mixing them in real-life situations (like
cleaning or cooking)?
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5. How does phenolphthalein help in identifying the nature of a substance?
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