Physical or Chemical Change? You decide!

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Activity 3 Physical and Chemical Changes
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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???
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Activity Series of Metals

• Li K Ba Sr Ca Na
  Mg Al Mn Zn Al(s)
  CuCl2(aq) ? AlCl3(aq) Cu(s)
  Fe Cd Co Ni Sn Pb H Cu Ag Hg
  Au

Decreasing Activity
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What do you see?
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Law of Conservation of Matter

• Matter can not be created or destroyed!
• Matter can only change forms!

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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.
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Physical Change
You still have bronze!
Melting bronze into a liquid
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Physical Change

• Ripping Paper

But this one cant be undone so easily.
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Origami
The form/shape may change, but you still have
paper
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Cracking an Egg
Beating an Egg
Another example of an irreversible physical
change.
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Hammering Metal
Malleability is a physical property of metals.
Malleable the ability to be hammered, pressed or
rolled into thin sheets without breaking is a
physical change.
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Ghost Crystals (crosslinked polyacrylamide)
water
Physical change!! Given time the water will
evaporate away and leave the crystals
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Sodium Polyacrylate
Theses crystals are found in the "super absorbent
layer" in most disposable diapers.
If left to dry long enough, it would return to
its original state or appearance.
It can absorb 200 to 300 times its weight in tap
water
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Physical Change Review

• Only the state of matter changes
• All Phase changes are physical changes
  (Solid---Liquid---Gas)!
• NO new substances are formed!
• Not all physical changes are reversible (crushing
  a rock).

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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.
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Raw Egg Fried Egg
COOKING
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Chemical Change! The proteins in the egg have
changed! The cooked egg cannot change
back to a raw egg.
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(No Transcript)
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Chemical Reaction!Your body chemically reacts
with the food you eat to make nutrients and
energy!
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Burning
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Chemical Change! Rust is a new substance! (color
change)
Car with rust
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PHOTOSYNTHESIS
6 CO2 6 H2O ? 6(CH2O) 6 O2
sugar
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Evidence of a Chemical Change

• Color Change
• Bubbling (formation of a gas)
• Light given off
• Temperature change
• Precipitate formed.

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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).

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Chemical Change Review

1. A chemical reaction occurs
2. New substance(s) are formed with NEW properties
3. It can not be reversed!

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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.
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Physical vs. Chemical

• physical
• chemical
• physical
• physical
• chemical

• Examples
• melting point
• flammable
• density
• magnetic
• tarnishes in air

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Yellow BlueSwitcheroo
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Yellow BlueSwitcheroo
Oscillating Reaction
Chemical! Color Change indicates the chemical
properties of the indicator were changed!
New product formed! Cant be reversed!
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Pour a Rainbow
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• Acids to a Base Reactions
• Color change Polymerization

A Chemical Change Occurs!!
We have now made our own slime!
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Old Foamy
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Old Foamy
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Chemical Change

• Old Foamy
• Hydrogen Peroxide Sodium Iodide Solution
• With Dishwashing Detergent
• New product formed!
• Cant be reversed!

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Whoosh Bottle
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Chemical Change

• Exothermic Reaction
• O2 Combustion ?CO2 H2O
• Color Heat released
• New product formed!
• Cant be reversed!