Acid In The Eye
Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★★☆ Can be done by science teachers
Safety: ★★★ Only to be attempted with adequate safety procedures and trained staff
Categories: Acids and Bases
Alternative titles:
Summary
This demonstration shows how strong acids and bases irreversibly damage proteins using egg whites as a model for the human eye. When acid is dropped on egg white, it denatures the proteins, turning them opaque and simulating permanent eye damage.
Procedure
- Place egg white in the Petri dish.
- Position the dish on an overhead projector or under a document camera (optional).
- Add several drops of a strong acid (such as hydrochloric, sulfuric, or nitric acid) to the egg white and observe it immediately become opaque.
- Attempt to rinse with water or sodium bicarbonate solution and note that the damage cannot be undone.
Links
Eye Safety Demo - All Things Chemistry:
📄 Acid in the Eye - Flinn Scientific: https://www.flinnsci.com/api/library/Download/a85735243805438b84ffa3fb05d121d7
📄 Acid in the Eye - Flinn Scientific: https://www.flinnsci.com/api/library/Download/a85735243805438b84ffa3fb05d121d7
Variations
- Try using acids of lower concentrations (though the effect is less dramatic).
- Repeat the experiment with sodium hydroxide solid or solution.
- Use different visual aids (such as slow-motion video or magnified projection) to highlight the denaturation process.
Safety Precautions
- Wear chemical splash goggles, chemical-resistant gloves, and a chemical-resistant apron.
- Perform nitric acid demonstrations in a fume hood, as it is toxic by inhalation.
- Do not eat or handle egg whites as food once used in the lab—they are treated as chemicals.
- Handle all acids and bases with care; they are corrosive and can cause severe burns.
Questions to Consider
- Why does the egg white become opaque when acid is added?
- How does denaturation change protein structure and function?
- Why can the damage not be reversed by rinsing?
- What does this experiment teach about the importance of wearing goggles in the lab?
- How is this related to real-life chemical exposure in the eyes?