Physical Changes
Lesson 2.3
Starter
Physical change
Glass
Several pieces
Change has occurred
Shape and size
Ice
Liquid water
Change has occurred
State of matter
No new substance
No new substance
Physical Change: is a change in size, shape, form or state of matter, but the matter’s identity stays the same.
Physical change
Examples: Change in shape and size in daily life
Cutting fruits and vegetables
Chewing food
Pouring juice from a bottle into a glass
Folding clothes
Dissolving of salt in water
Physical change
Examples: Change in state of matter
Physical change
Temperature (ºC)
Solid
Melting point
Solid + Liquid
Liquid
Liquid + gas
gas
Boiling point
Adding thermal energy
Solid 🡪 liquid (melting)
Liquid 🡪 gas (evaporation)
Note: Read about this diagram from the book
Physical change
Solid
Liquid
Gas
Solid + Liquid
Liquid + Gas
Physical change
Adding thermal energy:
When thermal energy is added to a solid
Particles move faster and temperature increases
Particles overcome the attractive forces and reach the melting point
Solid changes to liquid
When thermal energy is added to a liquid
Particles move faster and temperature increases
Particles overcome the attractive forces and reach the boiling point
Liquid changes to gas
Physical change
Some solids changes directly to a gas without becoming a liquid in a process called sublimation
Solid 🡪 Gas (Sublimation)
Physical change
Removing thermal energy
How would the diagram look if the graph showed the effect of removing thermal energy instead?
Liquid 🡪 solid (freezing)
gas 🡪 liquid (condensation)
Gas
Gas + Liquid
Liquid
Solid
Liquid + Solid
Physical change
Removing thermal energy:
When thermal energy is removed from a gas
Particles move slower and temperature decrease
Particles now are close to each other and reach the condensation point
Gas changes to liquid
When thermal energy is removed from a liquid
Particles move slower and temperature decrease
Particles now are close to each other and reach the freezing point
Liquid changes to solid
Physical change
Deposition is the change from gas directly to solid
Gas 🡪 Solid (Deposition)
Physical change
Melting: The change from solid to liquid
Freezing: The change from liquid to solid
Boiling: The change from liquid to gas
Condensation: The change from gas to liquid
Sublimation: The change from solid to gas
Deposition: The change from gas to solid
Restart
X
X
X
X
X
X
X
X
X
O
O
O
O
O
O
O
O
O
3
2
1
6
5
4
9
8
7
Physical change
Physical change
Dissolving:
Dissolving is a physical change. If you boil the water, the liquid water will change to vapor, leaving the salt behind.
Conservation of Mass
Particles before the physical change = Particles after the physical change
mass before the physical change = mass after the physical change
200 g
200 g
60 g
60 g
Conservation of Mass
Conservation of Mass
30 g