AIR AND WATER ( CLASS 5)

CHAPTER 11: AIR AND WATER

AIR

Air a mixture of different gases. Nitrogen and oxygen are mostly found in nature.

Gases present in the air

Air contains oxygen, carbon dioxide, nitrogen, dust , water vapour, smoke and germs.

 ATMOSPHERE

Our earth is covered by a layer like a blanket which protect us is called atmosphere.

 Atmosphere helps in following ways.

1.    It protects the earth from becoming too hot by stopping the harmful sun’s rays.

2.    It also helps in escaping the heat from the earth.

 Properties of air

Air occupies space, has weight and exerts pressure.

Air pressure

As we know, the air in the atmosphere is made up of a number of gases. These gases press down on the Earth’s surface, exerting a force that we call atmospheric pressure or air pressure. Although we are usually unaware of this pressure, it actually presses down very hard – roughly equivalent to the force of an elephant balancing on a desk!

Uses of air pressure in our daily life.

1.      We use air pressure to drink juice from a straw.

2.      While filling the ink inside a pen.

WATER

Water is the most important liquid on Earth.  All plants and animals need water to live.

Water cover almost 75% of Earth’s surface in the form of oceans, rivers, and lakes but very little of this water is fit for use.

Water impurities.

Any substances that makes the water dirty is the water impurities.

Two kinds of impurities -

Soluble impurities- which are soluble in water --- salt ,

Insoluble  impurities – which are in soluble in water –mud, oil.

REMOVING SOLUBLE IMPURITIES

EVAPORATION- changing of water into vapour on heating.

DISTILLATION- is a process of getting pure water by evaporation and condensation.

REMOVING INSOLUBLE IMPURITIES

1.      Sedimentation-EXPERIMENT FOR YOU

Take a platic bottle, fill sand and water to it shake the bottle and leave it for some time ,you will find

The sediments have settled.

2.      Decantation

Without disturbing the water pour the water in to a mug,

3.      Filtration

Make a filter paper and than pour the water. [refer book ]

JOURNEY OF WATER TO OUR HOME

The clean water we get in our taps is first treated before being supplied.

Water is treated by

1.      sedimentation,

2.      filtration, chlorination and

3.      storage {refer book page 107}