Module III - Ionic Phenomena

Objectives 2.1 To identify the properties normally

used to classify substances in aqueous solutions as either acids, bases, or salts.

2.2 To determine the conditions under which substances will show the

properties of acids, bases, or salts.

ACIDS, BASES AND SALTS

ACIDS BASES

SALTS

Substances

The word acids comes from one of its characteristic properties, its taste.

ACIDS = “acidus” (latin word) meaning sour.

ACIDSAcids

Bases are substances that are very slippery to touch and have

a strong bitter taste.

BASES Bases

SALTS

Salts are a source of ions that are easily absorbed by living organisms.

They are often used to change the physical properties of various solutions by lowering the

freezing points or raising the boiling points

Salts

ElectricalConductivity

Magnesium Taste/Touch

LitmusPaper

ACID YES Reaction Sour Turns red

BASE YES No ReactionBitter/

Slippery Turns Blue

SALT YES No Reaction SaltyDepends on the solution

Electrolytes – solutions that conduct electricity

Properties of Acids, Bases and Salts

Litmus paper is a type of indicator(thin strip of paper that is dipped into a solution)

2 Types: Blue Litmus Paper Red Litmus Paper

ACIDS – Turn blue litmus paper red

BASES – Turn red litmus paper blue

(USED TO DETECT ACIDS OR BASES)

BB

SALTS – not all salts are neutral - can be either acidic or basic (test with litmus paper)

Indicators

Phenolphthalein is another type of indicator

Bases turn clear phenolphthalein pink

Indicators

Chemically neutral – means does not contain an acid or

base

“Making a solution chemically neutral”

Neutralize it with a base

Neutralize it with an acid

Acids and bases neutralize each other forming a salt and waterEx. Acid + Base = Salt + water

Acids, bases and salts conduct electricity

Tap water -will conduct

-(free ions around)

Distilled water -does not-conduct

-(no free ions!)

o Review chart: (very important!)Electrical

ConductivityMagnesium Taste/

TouchLitmusPaper

ACID YES Reaction Sour Turns red

BASE YES No ReactionBitter/

Slippery Turns Blue

SALT YES No Reaction SaltyDepends on the

solution

Worksheet # 1 Study guide, Module 3, page 2

References

Science Quest, Grenier,Daigle & Rheaume, 1998

Physical Science Student Study Guide 416-436

Animation Factory Google Images