Phase Changes

1
Phase Changes

• Phase change the reversible physical change that
  occurs when a substance changes from one state of
  matter to another
• Six Phase Changes Melting, Freezing,
  Vaporization, Condensation, Sublimation,
  Deposition

2
Phase Changes

• Temperature and Phase Changes
• The temperature of a substance does not change
  during a phase change
• Ex) Naphthalene? freezing melting point 80C
• melting boiling points 218C

3
Phase Changes

• Energy and Phase Changes
• Energy is either absorbed or released during a
  phase change (direction depends on the type of
  phase change)
• Endothermic reactions the system absorbs energy
  from its surroundings
• Ex) Ice Sculpture will melt when the temperature
  rises above 0C

4
Phase Changes

• Heat Fusion the energy a substance must absorb
  in order to change from a solid to a liquid
• This varies from substance to substance
• Example ) 1 gram of ice absorbs 334 J of energy
  as it melts

5
Six Common Phase Changes

• Melting- temperature at which a substance changes
  from solid to liquid.
• Freezing temperature at which a substance
  changes from a liquid to a solid.
• Vaporization substance changes from a liquid to
  a gas. (Heat of Vaporization- energy a substance
  must absorb in order to change from a liquid to a
  gas.)

6
Six Common Phase Changes

• 4. Condensation- substance changes from a gas or
  vapor to a liquid.
• 5. Sublimation substance changes from a solid
  to a gas or vapor without changing to a liquid
  first (endothermic) http//www.windows.ucar.edu/to
  ur/link/comets/sublimation.html
• http//www.infoplease.com/ce6/sci/A0847062.html
• 6. Deposition substance changes directly into a
  solid from a gas without first changing to a
  liquid (exothermic)