What Happened in Activity 3? Solid Aluminum was added to a solution of Copper (II) chloride Al (s) + CuCl 2(aq) → ? Name a physical change that occurred???

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!