Here's how to tell the difference:
* Chemical Reactions: These involve the formation of new substances with different chemical compositions. This means atoms are rearranged to form new bonds.
* Examples: Burning wood, cooking an egg, rusting iron
* Key indicators: Change in color, odor, gas release, precipitate formation, heat or light production.
* Physical Changes: These involve a change in the form or appearance of a substance but not its chemical composition. No new substances are formed.
* Examples: Melting ice, boiling water, dissolving sugar in water
* Key indicators: Change in state (solid, liquid, gas), shape, size, or volume.
To tell if a specific reaction is chemical or physical, you need to consider the changes occurring. For example:
* Burning wood: This is a chemical change because wood reacts with oxygen to produce ash, carbon dioxide, and other substances.
* Melting ice: This is a physical change because the water molecules just change from a solid to a liquid state, but their chemical composition (H2O) remains the same.
In short, "reactions" can be either chemical or physical. It's important to specify the reaction to determine its nature.
