PHYSICAL & CHEMICAL CHANGES Objectives: 1. Compare and contrast physical and chemical changes 2....
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Transcript of PHYSICAL & CHEMICAL CHANGES Objectives: 1. Compare and contrast physical and chemical changes 2....
PHYSICAL & PHYSICAL & CHEMICAL CHANGESCHEMICAL CHANGES
Objectives:Objectives:
1.1.Compare and contrast physical and chemical Compare and contrast physical and chemical changeschanges
2.2.Identify examples of physical and chemical Identify examples of physical and chemical changeschanges
Why do I care?
Physical and Chemical changes occur around us everyday! Understanding them will help us better understand our world.
Changes in MatterChanges in Matter
Change: the act of altering a substance In science, we talk of two types of
changes:
physical
chemical
Physical ChangePhysical Change Physical change: a change that occurs that does
not change the identity or make up of the substance Change in state or phase (Freezing, boiling,
melting, sublimating) Changing shape (cutting, folding, twisting,
bending) Dissolving
Physical ChangesPhysical Changes Physical changes are changes that alter the size,
shape, location or physical state of a substance but not its chemical state.
Its still H2O- frozen in snowflakes, as liquid in raindrops, or as a gaseous water vapor, it’s chemical formula has not changed.
ExamplesExamples A physical change in a substance doesn't
change what the substance is. Cutting, folding, or crumpling paper –
A physical change in the shape and size of the paper. However, it is still paper! https://www.youtube.com/watch?v=kK4EMUd9eds
Dissolving sugar in iced tea- Sugar is still C6H12O6 but now it is spread out in
the liquid, it still tastes just as sweet! https://www.youtube.com/watch?v=D1dRdYPRvpY
What Other Kinds of Changes Are What Other Kinds of Changes Are Physical?Physical?
CuttingCutting TearingTearing ShreddingShredding ShrinkingShrinking EnlargingEnlarging
Change in Phase Change in Phase RelocatingRelocating RotatingRotating Molding (shaping)Molding (shaping)
Chemical ChangesChemical Changes
Chemical change: a change that occurs causing the identity of the substance to change Burning Chemically digesting food (acid and bile) Reacting with other substances
A chemical change is also called a chemical reaction
Chemical ChangesChemical Changes Chemical changes are changes that alter the
chemical make up of the substance. New matter is formed with properties that are
different than those of the original matter.
Chemical ChangesChemical Changes If you end up with a chemical or chemicals
that you did not start with. . . It is a chemical change!
Chemical ChangesChemical Changes A chemical change is not easily reversed.
Easy to reverse/change back
Difficult to reverse/change back
Signs That a Chemical Change Signs That a Chemical Change has occurredhas occurred
Creation of a gas (bubbles) https://www.youtube.com/watch?v=OBdgeJFzSec
Creation or loss of heat https://www.youtube.com/watch?v=GQkJI-Nq3Os
https://www.youtube.com/watch?v=UMEbeyKrE30
Burning Rotting/molding https://www.youtube.com/watch?v=CcuWuKLoCmU https://www.youtube.com/watch?
v=S12zZhdOckc&src_vid=OmcXo9XC6Uc&feature=iv&annotation_id=annotation_14756
Breaking down (decomposition) Precipitation https://www.youtube.com/watch?v=98dbILqPtgI
Cooking https://www.youtube.com/watch?v=n6wpNhyreDE
Rusting (oxidation)
Chemical ChangeChemical Change
Heat and light are often
evidence of a chemical change.
The strike of a match is a chemical change due to the
reaction of the chemicals with oxygen.
Burning wood turns to charcoal and ashes. This is a chemical change.
Is it Physical or Chemical?Is it Physical or Chemical?
ChangeChange PhysicalPhysical ChemicalChemical
Melting cheeseMelting cheese
Burning woodBurning wood
Milk souringMilk souring
Folding up paperFolding up paper
Bicycle rustingBicycle rusting
Start physical changes challenge PowerpointStart physical changes challenge Powerpoint