matter : physical vs. chemical

Matter: Physical vs. Chemical

Properties of Matter• Characteristics that enable us to

distinguish one kind of matter from another.

• How can we distinguish hydrochloric acid from water?

Types of Properties• Extensive

– Depends on the amount of matter – e.g., volume, mass, amount of energy

(cal)• Intensive

– Does not depend on the amount of matter

– e.g., melting point, boiling point, density, conductivity

Physical & Chemical Properties

• Physical Property–Can be observed or measured

without changing a substance’s composition.

Boiling Point

Density

Melting Point

MalleabilityConductivity

Color

HardnessMagnetism

Ability to transmit light

Physical & Chemical Properties

• Chemical Property–Can only be observed by

changing the composition of the material

–Changes its identity

The ability of a substance to…Rust

DecayBurn

React with acid, base, or water

Ferment

Properties of Water• Water expands as it freezes.

(Physical)• Hydrogen peroxide, H2O2 can decompose to

produce water. (Chemical)

• Water boils quicker in Denver, CO than at the beach. (Physical)

• When an electrical current is passed through water, elemental hydrogen and oxygen are produced. (Chemical)

• Salt can dissolve in water. (Physical)

Physical & Chemical Changes

• Physical Change–Will change the visible

appearance, without changing the composition of the material

–Changes that effect only physical properties.

–Does not change the composition!

Physical Changes

• Boil• Melt• Freeze• Distillation• Sublimatio

n• Expand

• Crush• Diffuse• Condens

e• Osmosis• Cut• Split• Crack

Physical & Chemical Changes

• Chemical Change–Changes that involve a

change in the composition of the substance.

–New matter is formed

Chemical Changes• Ferment• Decay/Decompose• React with acid, base, or water

• Neutralize• Rust• Digest• Tarnish• Explode / Burn• Ignite• Cook

2H2O 2H2 + O2

• Reactants the stuff you start with

• Products- what you make

• Arrow points from the reactants to the new products• The products will have NEW

PROPERTIES different from the reactants you started with

Indicators of Chemical Change

1. Color Change2. Gas produced 3. Temperature

change4. Light produced5. Precipitate forms6. Irreversibility

– Not easily reversed!

• Color Change–Very hard to reverse–Think about cooking an

egg

Indicators of Chemical Change

• Gas produced– Bubbles are produced– Careful there are

examples of bubbles that are not chemical – boiling water bubbles• Physical change Water

vapor starts to form inside the liquid in the form of bubbles

Indicators of Chemical Change

• Temperature change–Heat given off- Exothermic

• Feels hot• Feel someone after they workout

they’re hot–Heat absorbed- Endothermic

• Feels cool• Sweating while working out

Indicators of Chemical Change

• Light produced–Striking a match flame

produced–Fireworks

Indicators of Chemical Change

• Precipitate forms– 2 liquids

solid + liquid

Indicators of Chemical Change

Law of Conservation of Matter

• In any physical or chemical change, matter is neither created nor destroyed.

• During any chemical reaction, the mass of the products is always equal to the mass of the reactants

• All the mass can be accounted for!!– Burning of wood results in products

that appear to have less mass as ashes.

– Where is the rest??

Law of Conservation of Matter