MATTER: IT TAKES UP SPACE AND HAS

MASS

Chapter 3Matter: Properties and Changes

Sections 3.1 and 3.2

Physical Properties of MatterExtensive properties…

depend on the amount of substance.

true-wildlife.blogspot.comMass

Length

Volume

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Intensive properties are…independent of the amount of matter.

Density

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Other intensive properties:Color

Hardness

Odor

Melting point

Boiling point

Physical Changes…

Type of ChangeReversible

Irreversible

ExampleDissolving a substance inwater and thenevaporating the water.Ripping a piece of paper

cracking an egg.

Examples

or Reversible or Irreversible?

How we get phase changes…Melting point Boiling point

Are these extensive or intensive properties?

Chemical Properties of Matter

Ability or inability of a substance to change into one or more different substances.

Original matter can NOT be recoveredA new thing is madeAlso called a chemical reaction

Examples

Evidence of a Chemical Change

Evidence that a chemicalchange may may haveoccurred:

Change in temperature

Change in colorOdor Gas bubblesAppearance of a solid

In this activity, soaking the penny in the zinc solution actually coated the surface of the penny with zinc atoms. When the zinc covered penny was heated, the copper atoms of the penny and the zinc atoms coating the penny mixed and turned gold in color. This mixing of metals is an alloy called “yellow brass.”

Cu Zn Brass

Is this an extensive or intensive change?

Placing copper, or a copper-coated penny, in a mixture of zinc metal and aqueous zinc chloride causes zinc metal to plate outon the copper surface. This reaction occurs due to electrochemical potential differences that result when different “forms” of zincsolid are contained in a solution of 1M ZnCl2. The driving force in this reaction is formation of a brass alloy on the surface of thecopper.

Zn2+(aq) + 2e– → ZnCu (alloy) Note: ZnZn = zinc that deposits on the granular zinc

ZnZn → Zn2+(aq) + 2e– ZnCu = zinc that deposits on the copperZnZn → ZnCu E = +1.0 V