Sound and light are really interesting signs that show when chemical reactions happen!

When a reaction occurs, you might hear cool sounds like fizzing or popping. These sounds often mean that gas is being made. For instance, when you mix vinegar and baking soda, you can hear it bubbling because carbon dioxide gas is forming.

Light can also be involved! Some reactions give off light, which is called chemiluminescence. A great example is glow sticks! When you break a glow stick, the chemicals inside mix and create a bright light. This tells you that a reaction is taking place.

Here are some important signs to look for:

1. Bubbles: Just like when vinegar and baking soda mix and create gas.
2. Color Change: Sometimes, when metals react with acids, they change to bright colors.
3. Temperature Change: Some reactions can get hot or cold, so you might feel a difference in temperature.

These signs help us understand when a chemical reaction is happening!