Physical Science 1Chapter 23 Acids Bases & Salts

Properties of Acids• A solution that produces H3O+, hydronium ion, when dissolved in water (H+ ions)• Acid comes from the Latin word acidus meaning "sharp".• pH range 0 – 6.9 • Acids taste sour• Acids are corrosive to metals• Acid will change blue litmus paper red

H

HH H H

H

ClClO O

–+

acid hydromium ion

The strength of an acid

• Strong acids – An acid that totally ionizes in an

aqueous solution. • That means every molecule

breaks apart

– Acid with a very low pH (0 – 4)

• Weak acids – An acid that only partially

ionizes in an aqueous solution. • That means not every

molecule breaks apart.

– They usually have a pH close to 7 (3-6).

- + - +

Properties of Bases• A solution that has an excess of OH- ions• Another word for base is alkali.• pH range 7.1 – 14• Bases taste bitter• Bases feel slippery• Base will change red litmus paper blue

H

H

HH H

H

N NO O–+

HH

H H

hydroxide ionbase

pH Scale• In 1909, the Danish

biochemist Sören Sörensen invented the pH scale for measuring acidity. 

• The scale range is from 0 -14– Acids 0 – 7– Neutral 7.0

– Bases 7 – 14

[H+] pH Example

Acids

1 X 100 0 HCl

1 x 10-1 1 Stomach acid

1 x 10-2 2 Lemon juice

1 x 10-3 3 Vinegar

1 x 10-4 4 Soda

1 x 10-5 5 Rainwater

1 x 10-6 6 Milk

Neutral 1 x 10-7 7 Pure water

Bases

1 x 10-8 8 Egg whites

1 x 10-9 9 Baking soda

1 x 10-10 10 Tums® antacid

1 x 10-11 11 Ammonia

1 x 10-12 12 Mineral lime - Ca(OH)2

1 x 10-13 13 Drano®

1 x 10-14 14 NaOH

Indicators• Organic substance whose

solution change color due to changes in pH

• The color of the hydrangea flower depends on the pH of the soil in which it is grown– Blue flowers are produced

in basic soil – Pink flowers are generated

in acidic soil

RED CABBAGE JUICE

Neutralization• ACID + BASE → WATER + IONIC SALT

• H-anion + cation-OH → H2O + Salt (CationBASE AnionACID)

• Equivalence point – when the neutralization is finished• neutralization animation• Examples

– NaOH (aq) + HCl (aq) → NaCl (aq) + H2O (l)

– KOH (aq) + HBr (aq) → KBr (aq) + H2O (l)

• acids & bases with indicator

• The Rainbow Connection Demonstration

• AUSD Classlink