• The two most important things without which we won't be able to live are air and water.
• The air is all around us in our environment, and we take it in when we breathe.
Figure 1: Use of water in various ways
• This air consists primarily of oxygen and nitrogen in addition to small amounts of other gases, bacteria, and viruses.
• Water is important to us in many ways.
• It is used for:Read More...
• The air that surrounds us is a mixture of several gases.
Figure 2: Pie-chart of air composition
• Air is colourless and tasteless and is made up of about 78% nitrogen, 21% oxygen and 1% is composed of small quantities of other gases such as carbon dioxide, ozone, hydrogen, helium etc.
• It is the Earth’s gravity that holds the layer of air around our planet.
• Oxygen is a colourless, tasteless, gaseous element which forms 1/5 of the earth's atmosphere.
• One oxygen molecule is made up of two atoms of oxygen.Read More...
PROPERTIES OF AIR
• Air can be greatly compressed.
• All the air in a space as big as a house can be squeezed into a small tank.
• On the other hand, air can expand almost indefinitely.
• If all the air was removed from the inside of a house and then 1 cubic foot of air was supplied, the air would expand throughout the building.
• Air also has weight.
• And one way we can tell that air exists is by observing some of the things it does.
For example, air can fill a balloon, and when it’s in the form of wind, it can move leaves and blow our hair around.
Let us understand with the help of an experiment:Read More...
• Like air, water is also essential for life.
• Water is the only substance on Earth that is in liquid form at the temperatures commonly found on the surface of our planet.
Figure 6: Water is in liquid state on the surface of the Earth
• Water is a universal solvent, i.e. most of the substances can be easily dissolved into it.
• This allows water to carry nutrients to cells, and carry waste away from them.
• In addition to this, water has the unique property of expanding as it freezes.Read More...
REMOVING IMPURITIES FROM WATER
• Water purification is the process of removing undesirable chemicals, biological contaminants, and suspended solids from contaminated water.
• Water is purified for human consumption (drinking water) but water purification may also be designed for a variety of other purposes.
Removing Insoluble Impurities:
• Insoluble impurities such as sand can be separated by:
• Sedimentation is a physical water treatment process used to settle out suspended solids in water under the influence of gravity.Read More...