Chapter 15 Section 2

1. Properties of Matter Chapter 15 Section 2

2. Look but don’t touch! • A physical property is any characteristic of a material that you can observe without changing the identity of the substance. • Color • Size • Shape • Density • Melting point • Boiling point • When you describe the appearanceof an object, you are describing/measuring the physical properties of that object.

3. Behavioral Issues • Some physical properties help to describe the behavior of a material. • Magnetism • Conductivity • Viscosity • Density

4. Don’t make me separate you! • We can take advantage of physical properties to separate a specific material from a mixture. • How would you separate a mixture of sunflower seeds and poppy seeds? • How would you separate a mixture of metal shavings and saw dust? • How would you separate dirt from mud? • How would you separate alcohol from wine?

5. Don’t lose your identity! • When a material freezes, boils, evaporates, or condenses, it undergoes a physical change. • These physical changes can mean a change in size, shape or state of matter. • What are the states of matter? • Solid • Liquid • Gas • Plasma These changes may involve a change in energy, but the kind of substance or identity of the element or compound does NOT change.

6. I said, don’t make me separate you! • Distillation is the process of separating a substance from a mixture through the use of evaporation and re-condensation. • If a mixture has two different liquids with different boiling points, one liquid can be removed from the other by heating the mixture. • The liquid with the lower boiling point will evaporate, leaving the second liquid behind. • Distillation is used in the extraction of oils from plants and in the liquor industry.

7. Physical Changes can be reversed! • Ice melts into liquid water and can be re-frozen. • Melting & Freezing • Liquid water can be boiled into steam and can condensed back to liquid water. • Evaporation & Condensation • Dry Ice can sublimate from solid to carbon dioxide gas and deposit back to dry ice. • Sublimation & Deposition

8. Chemical Properties and Changes • A chemical property is a characteristic of a substance that indicates whether it will undergo a chemical change. • Flammable • Corrosive • Oxidizer • Photosensitive

9. Chemical Changes • A chemical change occurs when one substance changes into another substance. • Elements will NOT change into other elements!!! • This is called alchemy! • It is possible for one compound to change into another compound. • This is called chemistry! Nicolas Flamel

10. Ugh, what’s that smell? • Indicators that a chemical change has occurred: • A change in smell • The release of a gas or vapor • A change in color • A change in temperature • The formation of a precipitate • Of course the only true way to know that a chemical change has occurred is when a new substance is produced. The Bog of Eternal Stench! Evidence of Chemical Changes

11. Okay you two, separate! • We can also use chemical changes to separate materials. • Many businesses involved in mining, will use chemicals reactions to separate metals from the ore that they are trapped in. • These chemical reactions involve chemical changes that separate the metal from the rock.

12. Chemical Changes CANNOT be reversed

13. Physical and Chemical Changes in Nature • Our great planet creates many different weather conditions. • Some of these weathering effects cause physical changes to the Earth’s surface. • Other weathering effects cause chemical changes to the Earth’s surface. • What examples of each can you think of?

14. Keep track of your Mass! • The law of conservation of mass, states that matter cannot be created or destroyed. It simply exists. • It can be rearranged or moved around. • This means that the mass involved in any kind of physical change or chemical change MUST be conserved. Mass Before Change = Mass After Change

15. Let’s review! • The following are examples of Physical and Chemical changes. Use what you have learned to tell what kind of change is occurring in each.

16. Examples • A wood log burns in a fireplace and turns to smoke and ash. • An ice cube is dropped into a hot fry pan where it flash evaporates. • Salt is dissolved into water. • Sugar is dissolved into water. • Little Suzy uses a boxed cake mix with water, eggs and oil to bake a cake. • Little Johnny dissolves a nail in acid. • Rain water flows through a valley carving away rock and soil. • Rain water soaks through the soil and dissolves limestone deposits to create a cave. • Lighting a candle. • Rust on a car.

17. Great Job! • Now we will work on a concept comparison routine!