Physical and Chemical Changes AKS 11: Distinguish between a physical and chemical change

Physical and Chemical Changes

AKS 11: Distinguish between a physical and chemical change

Concept of Change

Matter: anything that has mass and volume

Change: the act of altering a substancePhysical or Chemical

Physical ChangePhysical change: a change that

occurs that does not change the identity of the substance.

Does NOT result in the production of a new substance

CAN be reversed easily by physical means

Can you think of ways I can make PHYSICAL changes to a piece of paper?

TearingCuttingRipping/shreddingFoldingGluing Writing on it

Physical Change Examples Melting ice(change in state or phase)

Freezing Kool-aid Tearing paper Bending a wire

Can you think of any more? Share with your elbow partner!

Chemical ChangesCHEMICAL change: a change that

occurs causing the identity of the substance to change

DOES result in the production of a new substance

CANNOT be reversed by physical means

A chemical change is called a chemical reaction

Can you think of ways I can make chemical changes to a piece of paper?

Burning itPouring acid on itEating it (digestion) – yuck!

Clues to a Chemical Change (Reaction)

As I burn a piece of paper, can you think of up to 6 clues that tell us that a chemical change has taken place?

Clues to a Chemical ChangeIndicators of a chemical change:

1. Production of a gas1. Fizzing, foaming, odor, bubbling

2. Production of energy (heat, light or sound)1. Light given off, feels hot or cold, hear noise(s)

3. Temperature Change1. Be careful with this one!

4. Unexpected Color change1. Be careful with this one!

5. Production of a precipitate (solid)1. Be careful with this one!

6. Production of a New Substance1. Only if the atoms that make it up have been chemically altered!2. The more of clues 1-5 you have, the more likely

Chemical Change Examples

Burning Digesting food Reacting with other substances

• Rusting, • corroding, • decomposing, • tarnishing

Is it Physical or Chemical?

Change Physical Chemical

Melting cheese

Burning wood

Milk souring

Wadding up paper

Bicycle rusting

Indicators of chemical reactionWhat indicators do you observe?2NI3 --- N2 + 3I2

Indicators of chemical reactionWhat indicators do you observe?C12H22O11 + H2SO4 --- 11H20 + 12C

Indicators of chemical reactionWhat indicators do you observe?IO3− + 2H2O2 + CH2(COOH)2 + H+ → ICH(COOH)2 + 2O2 + 3H2O

Indicators of chemical reactionWhat indicators do you observe?