Physical

1
Chapter 3

• Physical Chemical Properties
• Physical Chemical Changes

2
Physical Properties

• Characteristics of a substance that can be
  observed without changing the identity of the
  substance.

Examples include mass, weight, volume, density,
color, shape, hardness, texture
3
Physical Changes

• when only the form of a substance changes
• example change in phase like solid ice to
  liquid water

4
Chemical Properties

• Properties that describe how a substance changes
  into new substances

• Examples include flammability, support for
  burning, and the ease with which it combines with
  other substances

5
Chemical Changes

• During a chemical change, substances are changed
  into different substances.
• In other words, the composition of the substance
  changes.

6
Physical changes do not change the chemical
composition of the substance

• Chemical changes create new substances that can
  not be undone.

7
Evidence of aChemical Change

1. Color change
2. Odor change
3. Energy change
4. Formation of a gas or solid
5. Not easily reversed

8
Color Changes

• As in the case of autumn leaves, a change in
  color is a clue to indicate a chemical change.

9
Color Changes

• Perhaps you have found a half eaten apple that
  turns brown. The reason is that a chemical
  change has occurred when food spoils.

10
Odor Changes

• It only takes one experience with a rotten egg to
  learn that they smell different that fresh eggs.
• When eggs food spoil, they undergo a chemical
  change.

11
EnergyAbsorbed or Released

• the release or gain of energy by an object
  indicates a chemical change

12
Energy is absorbed during
chemical changes
involved in cooking, like baking a cake
13
Energy Released

• Energy can also be released during a chemical
  change.
• Fireworks release energy in a form of light that
  you can see.

14
Reaction of Sodium With Chlorine
Na
Cl

• You can also see that energy is released when in
  this movie clip sodium chlorine are combined
  with water.

15
Productionof a Solid

• A solid that separates out of solution during a
  chemical change is called a precipitate.

16
Productionof a Gas

• The formation of a gas is a clue to chemical
  changes.
• The bubbles of gas that you observed form when an
  antacid is dropped into water is an example.

17
Physical Easily reversed

• After ice melts into liquid water, you can
  refreeze it into solid ice if the temperature
  drops.

Freezing melting are physical changes
18
Chemical- Not easily reversed

• The substances produced during chemical changes
  however cannot easily change back into the
  original substances like when you burn wood.

19
Chemical Reactions

• Chemical Changes are also called Chemical
  Reactions.
• Chemical reactions involve combining different
  substances.
• The chemical reaction produces a new substance
  with new different physical and chemical
  properties.

20
Law of Conservation of Mass

• Matter is never destroyed or created in chemical
  reactions.
• The particles of one substance are rearranged to
  form a new substance.
• The same of particles that exist before the
  reaction exist after the reaction.