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What Happened in Activity 3?
Solid Aluminum was added to a solution of Copper (II) chloride
Al(s) + CuCl2(aq) → ?
Name a physical change that occurred???
How do you know it was a physical change???
Name a chemical change that occurred????
How do you know it was a chemical change???
Activity Series of MetalsLiKBaSrCaNa
Mg Al MnZn Al(s) + CuCl2(aq) → AlCl3(aq) + Cu(s)
FeCdCoNiSnPbHCuAgHgAu
Decreasing A
ctivity
What do you see?
Law of Conservation of Matter
Matter can not be created or destroyed!
Matter can only change forms!
Physical change The material itself is the same before and after the
change. The change can usually be
“undone.”
Ice melting: an example of a
physical change.
Melting bronze into a liquid
Physical ChangeYou still have bronze!
Physical Change
Ripping PaperBut this one can’t be undone so easily.
Origami
The form/shape may change,
but you still have paper
Cracking an Egg
Beating an EggAnother example of an irreversible physical change.
Hammering Metal
Malleable: the ability to be hammered, pressed or rolled
into thin sheets without breaking is a physical change.
Malleability is a physical property of
metals.
Ghost Crystals (crosslinked polyacrylamide) + water
Physical change!!
Given time the water will evaporate away and leave the
crystals
Sodium Polyacrylate
Theses crystals are found in the "super absorbent layer" in
most disposable diapers.
It can absorb 200 to 300 times its weight in tap water
If left to dry long enough, it would
return to its original state or appearance.
Physical Change Review
1.Only the state of matter changes2.All Phase changes are physical
changes (Solid---Liquid---Gas)!3.NO new substances are formed!4.Not all physical changes are
reversible (crushing a rock).
Chemical Change The substances present at the
beginning of the change are not present at the end;
new substances are formed. The change cannot be “undone.”
A nail rusting: an example of chemical change.
Raw Egg Fried Egg
COOKING
Chemical Change!
The proteins in the egg have changed! The cooked egg cannot
change back to a raw egg.
Chemical Reaction!Your body chemically reacts with the food
you eat to make nutrients and energy!
Burning
Car with rust =
Chemical Change! Rust is a new substance!
(color change)
PHOTOSYNTHESIS
6 CO2 + 6 H2O → 6(CH2O) + 6 O2
sugar
Evidence of a Chemical Change
• Color Change
• Bubbling (formation of a gas)
• Light given off
• Temperature change
• Precipitate formed.
Chemical Reaction!Formation of a Precipitate
lead iodide (PbI2), forms from the
mixture of two clear liquids,
potassium iodide (KI) and
lead nitrate (Pb(NO3)2).
Chemical Change Review
1. A chemical reaction occurs
2. New substance(s) are formed with NEW properties
3. It can not be reversed!
Macroscopic Definition
Microscopic Definition
Physical Change
The matter is the same.The original matter can
be recovered.
The particles of the substance are broken apart,
and the atoms are rearranged.
Chemical Change
The matter is different. The old matter is no longer present. The
original matter cannot be recovered.
The particles of the substance are broken apart,
and the atoms are rearranged into new
particles, forming a new substance.
Physical vs. Chemical
• Examples:
– melting point
– flammable
– density
– magnetic
– tarnishes in air
physical
chemical
physical
physical
chemical
Yellow & BlueSwitcheroo
Yellow & BlueSwitcheroo
Chemical! Color Change indicates the chemical properties of the indicator were changed!
New product formed!
Can’t be reversed!
Oscillating Reaction
Pour a Rainbow
Acids to a Base Reactions
Color change & Polymerization
A Chemical Change Occurs!!
We have now made our own slime!
Old Foamy
Old Foamy
Chemical Change
Old Foamy
Hydrogen Peroxide & Sodium Iodide Solution
With Dishwashing Detergent
New product formed!
Can’t be reversed!
Whoosh Bottle
Chemical Change
Exothermic Reaction:
O2 + Combustion CO2 & H2O
Color & Heat released
New product formed!Can’t be reversed!
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