Water Evaporation and Condensation

Back to: Basic Science Primary 4

 

Welcome to class! 

In today’s class, we will be talking about water evaporation and condensation. Enjoy the class!

Water Evaporation and Condensation

Introduction

ln previous classes,  we have learnt so much about sources of water,  uses of water,  how objects float and sink in water,  and also how water can be purified or made clean enough for consumption. In this lesson, we are learning more about water. We will learn what is meant by evaporation,  condensation and freezing.

 Differentiating water from other liquids

Water is a liquid substance which is odourless,  colourless and tasteless in its pure and undiluted form. Water is a major component of plants and animals;  it forms about 70% of the human body weight. Every living organism needs water to survive.

We have other substances which are also liquids, but they are different from water. Examples of other liquids are petrol, kerosene, bottled drinks,  alcoholic drinks,  groundnut oil as well as palm oil.

Activity

Observe the following liquids and record as indicated:

Liquid substance	Colour	Taste	Smell
Water
Palm Oil
Groundnut Oil
Zobo drink
Pepsi

Evaporation

Evaporation is said to occur when water is heated, and it gradually turns into gas called vapour and escapes into the atmosphere. So, we can define evaporation as a process whereby a liquid substance gradually changes into its gaseous form. The gaseous form of water is also known as steam. The solid form is called Ice.

Evaporation also takes place:

1. When we sweat during sports or intense activity
2. From the surfaces of water bodies like sea and ponds
3. After rain, water on the surface of the soil dries up because the water evaporated.
4. Evaporation occurs when there is wind. That is why our clothes dry faster with wind

Evaluation

1. What is evaporation?
2. What is the solid and gaseous form of water called?

 Condensation

Condensation can be defined as the process whereby vapour changes back to water when it comes in contact with a cooler surface.

Activity

1. Hold a cup containing ice over a boiling kettle which is giving off steam.
2. What do you observe?

Freezing

Water is in its liquid state;  however, it can be changed into the solid-state in the process called freezing. Freezing is the process by which water turns to ice when the temperature is lowered.

Uses of water

1. Water is used for domestic purposes like drinking,  bathing etc.
2. It is used in industries to mix chemicals and for other things
3. It serves as a means of transportation,  for ships,  boats,  canoes etc to travel on.
4. Water aids digestion
5. Water is a major component of plants and animals.
6. It serves as habitat for some organisms like fish,  crab, prawn, crocodile, etc
7. Plants need water to germinate and grow.

Evaluation

1. Explain the following terms
2. Evaporation
3. Condensation
4. Mention five uses of water.

Assignment

1. How do you know that water is pure?
2. Mention the three states of water
3. Explain the term freezing

 

In our next class, we will be talking about the Feeding System – Teeth, Tongue and Lips.  We hope you enjoyed the class.

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