Evidences of Chemical Reaction

Identifying a Chemical Reaction

• Chemical reactions involve a chemical change.
• In a chemical reaction, one or more substances are destroyed, and one or more new substances are created.

Indicators of a Chemical Reaction

1. Change in Color
2. Formation of a Gas
3. Formation of a Precipitate
4. Change in Odor
5. Change in Temperature
6. Emission of Light and Heat

Examples of Chemical Reactions

• Painting a wall blue: X (No chemical reaction)
• Mixing baking soda and vinegar: Chemical reaction occurs, indicated by the production of gas.
• Ice cream melting: X (No chemical reaction)
• Burning natural gas: Chemical reaction occurs, often detected by a change in temperature and emission of light and heat.
• Roasting a marshmallow until it turns brown: Indicates a chemical reaction, as evidenced by a change in color.

Exercise

• Determine whether each scenario involves a chemical reaction or not:
  • Painting a wall: X
  • Mixing baking soda and vinegar: ✓ (chemical reaction)
  • Ice cream melting: X
  • Burning natural gas: ✓ (chemical reaction)
  • Roasting a marshmallow: ✓ (chemical reaction)