* Chemical Reaction: Magnesium (Mg) reacts with water (H₂O) to produce magnesium hydroxide (Mg(OH)₂) and hydrogen gas (H₂). The chemical equation for this reaction is:
Mg + 2H₂O → Mg(OH)₂ + H₂
* New Substances Formed: The original substances, magnesium and water, are transformed into entirely new substances, magnesium hydroxide and hydrogen gas. This is a key indicator of a chemical change.
* Irreversible Change: The reaction is irreversible; you can't simply separate the hydrogen gas from the magnesium hydroxide and get the original magnesium and water back.
Why boiling water alone is not a chemical change:
Boiling water is a physical change. The water molecules are simply changing state from liquid to gas (steam), but their chemical composition (H₂O) remains the same. You can condense the steam back into water, reversing the process.
In summary: The reaction between magnesium and boiling water produces new substances, making it a chemical change.
