Acids & Alkalis

Acids & Alkalis

By Dr. Sanmi Olade

What are Acids

● Acids are substances that

produce Hydrogen ions when
dissolved in water.

Properties of Acids

●Acids have pH values less than 7.

●Acids pH values is from 0 (zero) to 6 (six).

●Acids taste sour

●Acids change the color of Litmus paper from Blue to Red.

●React with metals to produce Hydrogen

What are Alkalis

● Alkalis are substances that

produce Hydroxide ions (OH- )
when dissolved in water.

Properties of Alkalis (Alkaline)

●Alkalis have pH values more than 7.

●Acids pH values is from 8 (eight) to 14 (fourteen).

●Acids taste bitter

●Acids change the color of Litmus paper from Red to Blue.

●React with metals to produce Hydrogen

Acids and Alkalis are

chemical opposites

What is a pH Scale

●A pH Scale lets us know if a substance is an Acid or an Alkaline.

●A pH Scale has a value from 0 to 14.

●A pH Scale value 0 to 6 means Acid

●A pH Scale 8 to 14 means Alkaline

What is an Indicator

An Indicator is a substance that changes colour when it is added to acidic or
alkaline solutions.

Example of Indicators are :

●

Litmus Paper

●

Universal Indicator

●

pH Probe

Litmus Paper

Acid turns Blue Litmus paper Red

Alkalis turns Red Litmus paper Blue

Litmus Paper in Water

Water does not change Blue Litmus paper color

Water does not change Red Litmus paper color

Universal Indicators

Universal Indicators are show different colours that depends on the level of
Acid or Alkalis added to it.

Acid Level

Alkaline Level

pH Probe

The pH probe is a device that can read the level
of Acid or Alkaline in a liquid.

Multiple Select

Examples of Indicators are

• pH Probe

• liquid tester

• Litmus Paper

• Traffic Indicator

Multiple Choice

Choose the items that are Alkalis (means contains Alkaline)

• Blood

• Vinegar

• Bleach

• Lemon

• Ammonia

What is Neutralisation

The reaction between Acid and Alkali is called neutralisation

Important Reactions

Acid combines with other substances to produce different reactions.

● Acid + Alkaline = Salt and Water

● Acid + Metal = Salt and Hydrogen

● Acid + Carbonate = Salt and Water and Carbon dioxide

Hazard Symbols

Hazard Symbols helps you understand the dangers in your environment.

Dangerous to Environment

Toxic

Hazard Symbols

Hazard Symbols helps you understand the dangers in your environment.

Oxidising

Gas Under Pressure

Hazard Symbols

Hazard Symbols helps you understand the dangers in your environment.

Explosive

Flammable

Hazard Symbols

Hazard Symbols helps you understand the dangers in your environment.

Caution - Harmful

Corrosive

Hazard Symbols

Hazard Symbols helps you understand the dangers in your environment.

Long-term Hazard

Naming Salts

When Acid is added to a Alkalis these Salts are formed:

●Sulphuric Acid forms a Sulphate salt.

●Hydrochloric acid forms a Chloride salt.

●Nitric acid forms a Nitrate salt.

●Carbonic acid forms a Carbonate salt.

●Phosphoric acid forms a Phosphate salt.