Describing Matter

Key Idea #5 Matter can be described by its physical, chemical, and characteristic properties.

What is Matter?

Matter is anything that has mass and takes up space.

Matter is the “stuff” that makes up everything in the universe.

Physical Properties

describe the object or substance can be observed or measured

without changing the identity of the substance

Examples of Physical Properties color odor size shape state (solid, liquid, gas, plasma) texture (smooth, rough, soft, bumpy) density (measured in g/ml and g/cm³) melting point/boiling point/freezing

point

Three Principle States of Matter

Solid Liquid Gas

Source: Nasa.gov

Chemical Properties are determined by the arrangement of atoms

in the molecules making up the object describe a object or substance based on its

ability to change into a new substance with different properties

cannot be observed with your senses; must be tested

aren’t as easy to observe as physical properties

Examples of Chemical Properties

pH: Battery acid is 0 Liquid drain cleaner is 14

Flammability burning wood forms ash and smoke

Reactivity when iron is exposed to moist air, it

reacts with oxygen to form rust.

Characteristic Properties

are most useful in identifying a substance

are properties that remain true for any given sample of a substance

Examples of Characteristic Properties

Boiling point Melting/freezing point Density

Chemical Activity of a Substance

Another characteristic property is the chemical activity of a substance.

Chemical activity is a substance’s ability to undergo a specific chemical change.

Example: When wood burns it combines with oxygen in

the air to produce ash, smoke, and light (glowing gases).

Shared Characteristic Properties

Many substances have some of the same characteristic properties as other substances.

If you have an unknown clear liquid substance, it is important to study at least two or three characteristic properties before you can accurately identify the substance.

Characteristic Properties

Substance BoilingPoint

Melting/Freezing Point

Density

Pure Water

100°C 0°C 1 g/ml

HydrogenPeroxide 107°C -26°C n/a

Rubbing Alcohol 82°C -89°C .786 g/ml

pH Scale

pH stands for potential of hydrogen. The pH scale ranges from 0 to 14. It measures how acidic or alkaline

(basic) a solution is. Googleimages.com

A pH of less than 7 means the solution is acidic.

A pH of more than 7 means the solution is alkaline (basic).

A pH of 7 means it is a neutral solution. Pure water has a pH of 7. The less pH, the more acidic the solution is. The more pH, the more alkaline (basic) the

solution is.Googleimages.com

Acids and Bases Acids

taste sour are corrosive to metals change litmus paper red become less acidic when mixed with bases

Bases taste bitter feel slippery change litmus paper blue become less basic when mixed with acids

pH Lab You will be working with a partner as you

rotate through the stations. You will be using an indicator called a pH test

strip to test each substance. Do not touch or taste any of the substances. If you spill something, let me know so I can

clean it up. When you finish testing each substance,

complete the answers on your lab sheet.

pH Lab Procedures Predict whether each substance is an acid or a base. Take turns testing the solutions in the plastic cups by

dipping a pH strip into the liquid for about 2 seconds. Take the strip out and "read" the pH within 10 sec. by

comparing the color of the strip to the pH color chart. Record the pH on your data chart for each of the

numbered solutions. Now determine if the solutions were acids (pH: 0 up to

7), neutral (pH 7) or bases (pH: above 7 to 14) Record this information on your data chart beside each

solution.

Common Acids

Name of Acid Formula Use

Acetic CH3COOH Vinegar

Carbonic H2CO3 Beverages

Hydrochloric HCl Digestion

Nitric HNO3 Fertilizer

Phosphoric H3PO4 Fertilizer

Sulfuric H2SO4 Car Battery

Common Bases

Name Formula Uses

Aluminum Hydroxide

Al(OH)2 Deodorant, antacid

Calcium Hydroxide

Ca(OH)2 Concrete, plaster

Magnesium Hydroxide

Mg(OH)2 Antacid, laxative

Sodium Hydroxide

NaOH Drain cleaner, soap

The pH of Common Substances

Number scale ranges from from 0 - most acidic to 14 - most basic (alkaline).

NOTE: pH values may vary between the same types of products because of different growing and processing methods.