Section 5: Changes in States of Matter

states of matter 1024x838 - Section 5: Changes in States of MatterMatter often changes.  When enough heat is added to liquid, it will begin to boil and turn into a gas.  The bubbles are water vapor, and as more heat is added, the bubbles become larger and larger. The boiling point of a liquid is the temperature at which the liquid begins to vaporize.  The added heat gives the molecules in the liquid more kinetic energy.  Vaporization is the change from a liquid state to a gaseous state.  Vaporization can be used to describe both boiling and evaporation.  Evaporation is vaporization that occurs only at the surface of a liquid.  It can occur at temperatures below the liquid’s boiling point.  If you leave a cup of water out on the counter unattended, eventually the water will evaporate.

When something is melting, it changes from a solid state to a liquid state.  The melting point is the temperature at which a solid melts.  When something freezes, it changes from a liquid state to a solid state.  The freezing point is the temperature at which a liquid freezes. Condensation occurs when there is a change from a gaseous state to a liquid state.  The condensation point is the temperature at which gas condenses.

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