Chapter 17: Change of Phase Flashcards
Matter exists in four common phases that involve transfer of internal energy
1) Solid phase (ice)
2) Liquid phase (ice melts to water)
3) Gaseous phase (water turns to vapor)
4) Plasma phase (vapor disintegrates to ions and electrons)
The phase of a material depends upon
The temperature and the pressure
Changes from solid, liquid, gas, and plasma require energy to be
Added/Transferred to the material and the added energy causes molecules to move more rapidly
A plasma globe is:
A clear glass container filled with noble gases that has a high-voltage electrodes in the center of the container
When voltage is applied a plasma is formed
Within the container
If you keep your fingers on the glass, you will provide a spot for
Energy to flow
Melting were the process of
Solid to liquid
Freezing were the process of
Liquid to solid
Vaporization were the process of
Liquid to gas
Condensation were the process of
Gas to liquid
Sublimation were the process of
Solid to Gas
Deposition were the process of
Gas to Solid
Evaporation
Change of phase from liquid to gas
Molecule in liquid
Move randomly, at various speeds and continually collide into one another
Some molecules gain kinetic energy while others
Lose kinetic energy during collision
Some of the energetic molecules escape from
The liquid and become gas
Average KE of the remaining molecules in the liquid decreases resulting in
Cooler water
The process of the evaporating
1) High Energy: Evaporating
2) Medium Energy: Pulled back into water
3) Lower Energy: Remain as liquid
Evaporation is important in cooling our bodies, preventing us from
Overheating
Water on our skin absorbs body heat as evaporation cools the body that help to
Maintain a stable body temperature
Evaporation is a
Cooling process
Sublimation
Form of phase change directly from solid to gas
Substances that have molecules weakly
Held together sublimate
Condensation
Change of phase from vapor/gas to a liquid and opposite of evaporation
Gas molecules near a liquid surface are attracted to
The liquid and they strike the surface with increased kinetic energy and becoming part of the liquid
Kinetic energy is absorbed by
The liquid resulting in increased temperature
Warming process from a gas
To a liquid
When temperature of the atmosphere is low, the water molecules in the air
Move slowly
Slow moving water molecules stick together, causing what?
Condensation
Fog and clouds are created when
Air rises and the molecules of water vapor combine to make tiny liquid water droplets that hang in the air
The way we see the fog by the
Tiny water droplet moving
Condensation (Cloud)
1) Warm air rises (less dense)
2) Warm air expands and chills
3) Water vapor molecules slow down and stick together
4) Water vapor molecules combine with other dust particles in the air to form cloud droplets that grows into cloud
Boiling process is a
Rapid evaporation from beneath the surface of a liquid
Forces due to combined pressure of
Atmosphere and water
Boiling process is a rapid form of
Evaporation beneath the surface forms vapor bubbles and the bubble rise to the surface
If vapor pressure in the bubble is less than the surrounding pressure (atm and water), then
The bubble collapse
Bubbles do not form at the temperature below
Boiling point (vapor pressure is insufficient)
Boiling water at 100 degrees Celcius is in
Thermal equilibrium
Boiling water is being
Cooled as fast as it is being warmed
Molecules with more KE are leaving then the
lower temperature and in this sense, boiling is considering a cooling process
Boiling point depends on
Pressure
Boiling point decreases with
Decreasing atmospheric pressure
Boiling point increases with
Increasing atmospheric pressure
The process of boiling
1) Cool the water being boiled
2) Depends on atmospheric pressure
3) Is a change of phase below the water surface
Melting
Change of phase from a solid to a liquid and the opposite of freezing
When heat is supplied to a
Solid and added vibration breaks molecules loose from the structure and melting occurs
Freezing
Change of phase from a liquid to a solid and opposite of melting
When energy is continually removed from a liquid, molecular motion decreases until
The force of attraction bind them together and formations of ice occurs
Substances freeze at
Exactly the same temperature as they melt
Under a specified pressure, the temperature and a liquid and solid exists in
Equilibrium is defined as the melting or freezing point
Melting and freezing temperature of water was
0 degree Celcius and 32 degrees Fahrenheit
Regelation
Phenomenon of melting under pressure and freezing again when the pressure is reduced
When pressure is removed, molecules was
Crystallize and refreezing occurs
From solid to liquid to gas phase
Add energy
From gas to liquid to solid phase
Remove energy
Energy is absorbed when change of phase is in this direction:
Right forward direction
Energy is released when change of phase is in this direction:
Opposite direction
When snow forms in clouds, the surrounding air is
Warmed
Heat of fusion (Lf)
Amount of energy needed to change any substance from solid to liquid and vice versa
Heat of Vaporization (Lv)
Amount of energy needed to change any substance from liquid to gas and vice versa
