Acid and Base. Meaning and Physical Properties


Acid and Base. Meaning, Types, and Physical Properties



Subject : 

Basic Science and Technology


Term :

Second Term



Week 9


Class :

Basic 5 / Primary 5


Previous lesson : 

The pupils have previous knowledge of meaning and types of rocks 


Topic :

Acid and Base.

Types and Physical

Properties of Acid and Base


Behavioural objectives :

At the end of lesson, pupils should be able to:

  • Define acid
  • Define base .
  • Mention types of acid and Base .
  • List the properties of acid and Base
  • Mention the uses of acid and Base



Instructional Materials :

  • Wall charts
  • Pictures
  • Related Online Video
  • Flash Cards
  • Textbooks
  • Workbooks
  • Water bottle
  • Sample rocks or stones

Methods of Teaching :

  • Class Discussion
  • Group Discussion
  • Asking Questions
  • Explanation
  • Role Modelling
  • Role Delegation


Reference Materials :

  • Scheme of Work
  • Online Information
  • Textbooks
  • Workbooks
  • 9 Year Basic Education Curriculum
  • Workbooks


Content :

What is acid  ?

An Acid is a chemical substance that can react with other materials which are sometimes sour or turn blue litmus paper to red  . They are used in specific places like laboratory, industry and research centers. Unripe fruits contain acid that is why if you taste an unripe orange it will be sour. Etc. Many people believe acids are harmful. For instance, a car or lorry battery contains sulfuric acid, without which it will not work. This acid irritates or burns the skin if it touches the human body. While some acids are harmful, some are not. Some acids are in fact edible (can be eaten).


Some acids occur naturally in living things. For example in the human stomach, there is an acid called hydrochloric acid. It is formed by cells in the stomach wall, and it helps digestion to take place. Orange juice, lemon juice and grape fruit contain ascorbic acid, which is vitamin C.


We must take vitamin C and other vitamins in our diet to maintain good health. Vitamin C is also present in vegetables and some other fruits. Sour milk and yoghurt contain lactic acid, while grape contain tartaric acid.


Types of Acid   

Types of acids

There are Natural acids and the Synthetics acids.


NATURAL ACIDS are called organic acids: this acid occurs naturally, they are found in plants and animals.


Ascorbic acid or acetic acid in vinegar

Citric acid in lime.

Lactic acid in spoilt milk.

Tartaric Acid in grape.


Synthetic acids are produced by human – beings (scientists) in the laboratory.


Hydrochloric acid

Acetic acid

Nitric acid

Sulphuric acid

Tetraoxosulphate (VI) acid.


They have sour taste.

Concentrated acids can are corrosive.

They turn blue litmus paper red.

The concentrated acid can react with plastic and metals and damage them.

They neutralize bases to form salt and water.


They are used in the manufacture of paint, fertilizers, drugs and other chemicals in dusty.

They are used as solvent.

They are used in the production of gasses like hydrogen, carbon dioxide.

They are used to produce chemicals in the laboratory.


Base are chemical substances that react with acid to form salt and water only. They are found in natural objects like wood ash, burnt palm, bunch of waste etc.

Types of Bases

The two types of bases are:

Soluble bases or alkalis bases: these are bases that are soluble in water. Examples are sodium hydroxide (caustic soda), potassium hydroxide (caustic potash).

Insoluble bases: these are bases that are not soluble in water, e.g. copper (II) oxide and Zinc Oxide.


Base has bitter taste.

Bases are slippery or soapy to touch.

They turn red litmus paper to blue.

Concentrated base are corrosive.


They are used in the production of soap.

They are used in the production of chemicals.

Some bases are used in the production of glass, drugs and detergents.

They are used in the production of salt when dissolved in acids.

Lime water (Calcium hydroxide), which is base is used in the production of plaster of Paris (POP).





The topic is presented step by step


Step 1:

The class teacher revises the previous topics


Step 2.

He introduces the new topic


Step 3:

The class teacher allows the pupils to give their own examples and he corrects them when the needs arise




The class teacher wraps up or conclude the lesson by giving out short note to summarize the topic that he or she has just taught.

The class teacher also goes round to make sure that the notes are well copied or well written by the pupils.

He or she does the necessary corrections when and where  the needs arise.



Evaluation . 

  • Define acid
  • What is a base
  • mention four characteristics of acid
  • Mention four uses of base
  • Mention some major landmark rocks in Nigeria




Prepare for the next lesson by reading about acid and base



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