AIM: What are chemical and physical changes? What are chemical and physical changes?
Physical vs chemical changes notes
Transcript of Physical vs chemical changes notes
Physical vs. Chemical ChangesNotes
TEKS 6.5D identify the formation of a new substance by using the evidence of a possible chemical change such as production of a gas, change in temperature, production of a precipitate, or color change.
TEKS 8.5E investigate how evidence of chemical reactions indicate that new substances with different properties are formed.
Matter undergoes changes all of the time.
There are two types of changes:
chemicachemicall
physicalphysical &&
Physical changes:
Physical changes occur when the appearance of a substance changes…
…but chemicalchemical
lyly the substance is the same.
The The individual individual molecules molecules
do not do not changechange..
Examples of Examples of physical physical
changes are, changes are, melting, melting, freezing, freezing,
or changing or changing sizesize or or shapeshape..
A A physical physical change change
also also occurs occurs when when
substancsubstances are…es are…
mixedmixed and and something something dissolvesdissolves…like …like making salt water making salt water or Kool-aid.or Kool-aid.
The water, salt The water, salt and sugar still and sugar still keep their keep their original original propertiesproperties and and the the substances substances can be can be separated separated again.again.
Chemical Chemical ChangesChanges
A A chemical chemical changechange occurs occurs
when the when the atoms making atoms making
up matter up matter rearrangerearrange....
to form a new to form a new substance substance with with new new
propertiesproperties. .
This usually This usually occurs during occurs during
a a chemical chemical reactionreaction. .
Evidence of Evidence of a chemical a chemical
change:change:
ProductiProduction of a on of a gas.gas.
bubblesbubblesfizzingfizzing
foamingfoamingsmokesmokeodor odor
color changecolor change*not all color *not all color changes are changes are
chemical!chemical!
A A differentdifferent color appearscolor appears
*not all color *not all color changes are changes are
chemical!chemical!
FormatioFormation of a n of a
precipitatprecipitatee
cloudinescloudinesss
foggyfoggy
solidsolid at at bottom bottom of of containercontainer
Change in Change in heatheat or or
light light energyenergy
SparksSparksexplosionexplosionglowingglowing
temperatutemperature re
increases increases or or
decreasesdecreases
These These are are only only
cluesclues……
……a chemical a chemical change has not change has not actually taken actually taken place unless place unless matter has matter has
changed into a changed into a new substancenew substance..
Some Some common common
examples of examples of chemical chemical changeschanges
include…include…
RustingRusting……
Tarnishing…Tarnishing…
Burning…Burning…
Cooking…Cooking…
Digesting…Digesting…
If you have the If you have the chemical chemical
equationequation, you , you can tell if a can tell if a chemical chemical
change has change has taken place taken place
by…by…
Looking to Looking to see if the see if the
products in products in the equation the equation
are….are….
differentdifferent from from the the
reactantsreactants..