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Changing state refers to the process where matter transforms from one physical state (solid, liquid, or gas) to another, typically due to changes in temperature or pressure. This process is a physical change, meaning. It doesn’t alter the chemical composition of the substance.

Key aspects of changing state:

• Energy:

  Changes in state usually involve the absorption or release of energy, typically in the form of heat. 

  
  

• Temperature:

  Temperature changes can cause matter to transition between states. For example, heating a solid (like ice) can cause it to melt into a liquid (water), and further heating the liquid can cause it to boil into a gas (steam). 

  
  

• Processes:

  Common processes involved in changing state include melting (solid to liquid), freezing (liquid to solid), evaporation/vaporization (liquid to gas), condensation (gas to liquid), sublimation (solid to gas), and deposition (gas to solid). 

  
  
  
  

  Examples:

  • Melting: Ice melting into water. 

  • Freezing: Water freezing into ice. 

  • Evaporation: Water evaporating from a puddle into the air. 

  • Condensation: Water vapor condensing on a cold surface. 

  • Sublimation: Dry ice sublimating directly from solid to gas. 

  • Deposition: Water vapor directly turning into ice crystals on a cold window. 

    
    

  Reversibility:

  Many changes of state are reversible. For example, you can freeze water (liquid) back into ice (solid).