Transcript physical change

Changes in Matter
Physical VS Chemical
Changes
I8A: The student knows that
changes in matter affect everyday
life. The student is expected to
distinguish between physical and
chemical changes in matter such as
oxidation, digestion, changes in
states, and stages in the rock cycle.
Day 2-#2
Physical Changes
In a physical change, the
form of a substance or
some of the substances
properties may change,
but its chemical
composition – the way its
atoms are put together –
remains unchanged. The
matter involved in a
physical change keeps its
identity!
www.julieleung.com/ archives/2004_07.html
Ice cream melting is a physical change.
Day 2-#2
Chemical Changes
In a chemical change,
the elements of one
compound
recombine to form
one or more new
chemical
compounds with
different properties.
www.pc.chemie.uni-siegen.de/.../ v44-1-1.html
2 Na + 2 H2O
> 2 NaOH + H2
To view this reaction go to: http://www.pc.chemie.unisiegen.de/pci/versuche/pics/anim/natrium.mpg
Day 2-#2
Signs of a Chemical Change:
1. Heat or light is
produced.
2. Gas is produced.
3. Precipitate forms.
Example of precipitate:
http://www.sfrisch.com/chem_cov.
Verbs to help you determine a
Physical VS Chemical Change:
Physical:
1. Evaporate
2. Melt
3. Heat
4. Condensation
5. Cool
6. Compress
7. Subduction
8. Shattering
9. Dissolving
Chemical:
1. Burning
2. Forming or Form
3. Becoming
4. Turning to
5. Rusting
6. Baking
7. Weathering
8. Combining
9. Damaging
Have a student:
1. Rip a sheet of paper
2. Grind or crush a piece of chalk
3. Place powdered chalk into a test tube and add 5%
acetic acid (vinegar)
4. Dissolve salt in water
5. Light a candle
1. Identify the following as
physical or chemical changes:
1. Liquid water
evaporates
2. Iron rusting
3. Salt dissolves in
water
4. Milk turning sour
5. Baking a cake
6. Burning wood
7. Fireworks
8. A gas condenses
to become a liquid
9. Ripping a sheet of
paper
10. Slicing a cake
Day 2-#2
The Rock Cycle
One of nature’s slowest processes – the rock
cycle – is a repeating series of physical and
chemical changes in which one type of rock
changes to another type.
Day 2-#2
http://science.cc.uwf.edu/sh/curr/rockcyc/rockcyc.htm
Day 2-#2
2. In the rock cycle, which of these is a
chemical change involved with the formation
of igneous rocks?
F Compression of sediments
G Heat loss from lava
H Subduction of plates
J Formation of minerals
Question is from TEA Released TAKS Test
Day 2-#2
3. Which of these changes in rocks is a
physical change?
A Acid rain damaging marble
B Iron in rock combining with oxygen to
form hematite
C Carbonic acid weathering limestone
D An ice wedge shattering a slab of shale
Question is from TEA Released TAKS Test
Day 2-#2
4. Which of the following processes is an
example of a physical change associated
with an oak tree?
A Decomposition of bark by bracket fungi
B Starches and sugars being broken down
during energy production
C Water and carbon dioxide being converted
to glucose
D Evaporation of water from the surfaces of
Leaves
Day 2-#2