CHAPTER 2

Matter and Change

B. Physical Properties

1. can be observed without changing the chemical composition

2. Examples Color Melting point Density Hardness Malleability

C. Chemical Properties

1. determined by how a chemical reacts (or doesn’t) with another chemical

2. Examples – Rusts Reacts with HCl Reacts with water

Physical or Chemical Property?

7) Water boils at 100°C.8) Zinc reacts with hydrochloric acid.9) Sodium chloride dissolves in water.10) Aluminum is shiny silver in color.11) Copper is ductile.12) Calcium reacts with water.13) The density of aluminum is 2.7 g / mL.

D. States of Matter

Solids

a) definite mass?b) definite volume?c) definite shape?d) compressible?e) able to flow?

D. States of Matter

Liquids

a) definite mass?b) definite volume?c) definite shape?d) can be

compressed?e) flows?

D. States of Matter

Gases

a) definite mass?b) definite volume?c) definite shape?d) can be

compressed?e) flows?

D. States of Matter 1) summary chart

Property Solid Liquid Gas

Mass Fixed Fixed Fixed

Volume Fixed Fixed Volume of container

Flows? No Yes Yes

Shape Fixed Shape of container

Shape of container

Compressible? No No yes

Expands? No No yes

D. States of Matter

2) Vapors

a) = substances in the gaseous state which are usually in the liquid or solid state at room temperature

b) ex. – gasoline fumes, moth ball odors, steam, “fog” from dry ice

E. Classification of Matter

1. Substances

= definite or fixed composition can write a chemical

formula for it pure

E. Classification of Matter

1. Substances

a) Elements Listed on periodic

table Mg, Ne, Cl, C, etc.

E. Classification of Matter

1. Substances

b) Compounds Contain two or more

elements in fixed ratio Ex. – NaCl, CO, H2O

E. Classification of Matter

2. Mixtures

= composition is NOT fixed or definite; it varies Cannot write a formula

for it

E. Classification of Matter

2. Mixtures

a) homogeneous mixtures*uniform (same throughout)*one phase*also called solutions

(but can be s, l or g)*ex. – saline solution, tap water, brass, hot tea, air

E. Classification of Matter

2. Mixtures

b) heterogeneous mixtures

*not uniform *two or more phases *ex. – soil, fresh-

squeezed orange juice, sand and water

F. How to separate parts of a mixture?

1. Magnetism

F. How to separate parts of a mixture?

2. Filtration

F. How to separate parts of a mixture?

3. Density

F. How to separate parts of a mixture?

4. Distillation (different boiling

points)

F. How to separate parts of a mixture?

5. Chromatography (ex. – paper + ink)

G. Changes

1. Physical Changes

a) chemical composition of material does NOT change

b) may be reversible

c) examples Tearing paper Boiling water Crushing salt Crumpling foil

G. Changes

2. Chemical changes

a) change in chemical composition

b) examples Iron rusting Zinc + hydrochloric

acid Digestion of food Burning wood Lithium + water

H. Clues for a chemical change (reaction)

1. formation of bubbles (gas)

Ex. – metal + acid

H. Clues for a chemical change (reaction)

2. formation of precipitate (insoluble powder)

H. Clues for a chemical change (reaction)

3. release or absorption of energy (heat or light)

Ex. – burning of wood

H. Clues for a chemical change (reaction)

4. change in color

Ex. – meat changes color when cooked

Ex. – changing in color of leaves in fall

H. Clues for a chemical change (reaction)

5. change in pH (acidity level)

I. Sometimes the “clues” indicate a physical change!

1. color change could be dilution (ex. – add water to Kool-Aid)

2. bubbles could be boiling liquid

3. heat absorbed during a change in state (ex. - melting ice)

J. Law of conservation of mass

1. Mass cannot be created or destroyed in a chemical reaction or physical change