demonstrations:thermochromic_materials
Thermochromic Materials
Materials: ★★★ Requires materials not commonly found in school laboratories
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required
Categories: Colour Changes, Materials
Alternative titles: Heat-Sensitive Color Change, Temperature-Activated Pigments
Summary
Thermochromic materials are substances that change color with temperature. They are used in novelty items, clothing, toys, and scientific demonstrations, allowing students to see a physical property that responds directly to heat.
Procedure
- Obtain a commercially available thermochromic item, such as mood rings, color-changing spoons, mugs, or thermochromic pigments.
- Warm the object by holding it in your hand, placing it in warm water, or shining a lamp on it.
- Observe the color change as the temperature shifts.
- Allow the item to cool back to room temperature and watch the color return.
Links
INTERESTING MATERIALS: Thermochromic Materials - Gabriele Mogni:
Color Changing Thermochromic Slime (Chemistry) - BeardedScienceGuy:
Smart Textiles - Thermochromic paint - Cheryl Sleboda Whited:
Variations
- Use different thermochromic products (mugs, slime, nail polish, stickers, fabrics).
- Compare how quickly items change color under different heat sources (hand warmth, hot water, hair dryer).
- Test durability by repeatedly heating and cooling the material.
Safety Precautions
- Use only safe, consumer-grade thermochromic products in the classroom.
- If using warm water, ensure it is not hot enough to cause burns.
- Do not overheat items (e.g., avoid direct flames).
Questions to Consider
- Why do thermochromic materials change color with temperature? (They contain pigments or liquid crystals that rearrange as temperature changes, altering light reflection.)
- Are these color changes physical or chemical changes? (They are physical changes, since the substance is not permanently altered.)
- Where might thermochromic materials be useful in everyday life? (In thermometers, baby spoons, battery testers, clothing, and safety indicators.)
- How do liquid-crystal thermochromics differ from pigment-based ones? (Liquid crystals shift structure with temperature, while pigments change molecular arrangement to absorb different wavelengths of light.)