Answer:
a phase change occurs when the pressure on the system changes. during pressure change on the system changes the object is going through the phase change of melted then solid, melting, liquid, and then vaporization. sense it is going from a solid state to a melting state. the particles are Freezing: liquid to solid. Melting: solid to liquid. Condensation: gas to liquid. Vaporization: liquid to gas. Sublimation: solid to gas. Deposition: gas to solid. during the a phase change the energy of the particles are The energy that is changing during a phase change is potential energy. During a phase change, the heat added increases or released decreases will allow the molecules to move apart or come together. a phrase change occurs because a phase change is when matter changes to from one state to another example: solid to liquid. another reason why a phase change occurs is because water is a substance that has many interesting properties that influence its phase changes. Most people learn from an early age that water melts from ice to liquid at 0°C, and boils from a liquid to a gas at 100°C but this isn't true in all circumstances. The pressure affects these transition points, so for water, the boiling point actually decreases as the pressure decreases.
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-Asher