GEN CHEM: LESSON 6&7

• The change from solid to liquid is called melting.
• The change from liquid to gas is called vaporization or evaporation.
• The change from solid to gas is called SUBLIMATION
• The change from gas to

  liquid is called CONDENSATION
• The change from gas to

  solid is called DEPOSITION
• The change from liquid

  to solid is called FREEZING
• Freezing example: Water turns to ice tube when exposed in low temperature.
• Deposition example: Water vapor turns to frost.
• Condensation Example: Water droplets on the outside of your cold drink.
• Sublimation Example: Naphthalene ball became smaller
• VAPORIZATION OR EVAPORATION Example: boiling water, steam,
• Melting Examples are ice tube turns into liquid / water
• These changes take

  place when heat is

  absorbed (heat

  gained). They are

  Endothermic

  Processes.
• Such modifications

  emit heat (heat lost)

  and are Exothermic

  Processes.
• A phase diagram is a

  graphical depiction of

  a substance's

  physical states under

  varying temperature

  and pressure

  conditions.
• A phase diagram is a

  graphical depiction of

  a substance's

  physical states under

  varying temperature

  and pressure

  conditions.
• The diagram is split

  between solid,

  liquid, and gaseous

  states.
• PHASE DIAGRAM

  The boundary

  between the liquid

  and gaseous

  regions stop at red

  dot, the critical point

  for the substance.
• The lines that serve as

  physical state borders

  represent the combinations

  of pressures and

  temperatures at which two

  phases can exist in

  equilibrium. In other words,

  these lines identify points

  for phase transition.
• phase Diagram

  The curve on a phase

  diagram which represents

  the transition between

  liquid and solid states.

  The green line divides the

  solid and liquid phases and

  represents melting (solid to

  liquid) and freezing (liquid to

  solid) points
• 
  

  The curve on a phaseThe curve on a phase

  diagram which represents

  the transition between

  gaseous and liquid states.

  The blue line divides the

  liquid and gas phases and

  represents vaporization (liquid

  to gas) and condensation (gas

  to liquid) points
• 
  

  The curve on a phase

  diagram which represents

  the transition between

  gaseous and solid states.

  The red line divides the solid

  and gas phases and

  represents sublimation (solid

  to gas) and deposition (gas to

  solid) points.
• How does a change in energy affect phase changes?

  Phase changes

  occur when heat

  is added or

  removed from a

  substance.
• The added energy is used by the substance in

  either of two ways when a substance is heated:

  a.The added heat increases the

  kinetic energy of the particles, and the

  particles move faster. The increase in

  kinetic energy is accompanied by an

  increase in temperature.

  b. The added heat is used between particles

  to break off attractive forces. There is no

  observed increase in temperature when this

  happens. Often a change in the physical

  appearance of the substance is observed, such

  as a phase change.
• Conversely, in two ways, the loss or release of heat

  results in:

  a.A decline in the particles' kinetic energy. The

  motion of the particles slows down. A decrease

  in temperature is observed.

  b. Forces of attraction are formed, and there

  may be a phase transition. No change in

  temperature is observed.
• If there is no specific value given in the diagram writhe the less than or greater than (<>)
• Green boundary: Solid to liquid

  Blue boundary: Liquid to gas

  Red boundary: Solid to gas
• There are two important points on the diagram,

  the triple point, and the critical point.
• Triple point: solid, liquid, & gas
• Critical point: liquid & gas
• 1 atm is the standard pressure.
• Phase diagrams are plots of pressure (usually in

  pascals) versus temperature (usually in degrees

  Celsius or Kelvin).