* Physical Change: A physical change alters the form or appearance of a substance but doesn't change its chemical composition. In this case, water molecules (H₂O) remain the same, whether they are in liquid or gaseous form.
* Chemical Reaction: A chemical reaction involves the formation of new substances with different chemical compositions. This is not happening when water changes state.
The Process: The change from liquid to vapor (evaporation or boiling) involves breaking the intermolecular forces holding the water molecules together in the liquid state. This requires energy, usually provided by heat. The water molecules then gain enough kinetic energy to overcome their attraction and escape into the air as water vapor.
Key Points:
* No new substances are formed: The water molecules themselves remain unchanged.
* The process is reversible: Water vapor can condense back into liquid water.
* It involves a change in state: Liquid to gas.
Let me know if you have any other questions!
