Water is a colourless and transparent chemical substance which is the main constituent of streams, oceans, lakes on the earth’s crust. It is an important fluid that plays a significant role in sustaining life on earth. The chemical formula of water is H2O. It is made up of two hydrogen atoms and one oxygen atom which are held together by covalent bonds.
Note: 71% of the earth’s surface is made up of water.
Water – An Important Source of Life
Water is the most valuable resource on Earth. Without it, life on our planet would not exist. Every living thing needs water and every living thing is made in part from water. Water is an essential part of our daily lives. The importance of water in our daily life is that we use it to drink, cook, bathe, wash our clothes and irrigate farms to grow crops. On average a human uses 365 litres of water per day.
States of Water
- The solid-state of water is known as ice. Water freezes at 0o Celsius (freezing point of water) to form ice.
- The liquid state of water makes up most of the earth’s surface. It finds its application in a wide range of areas.
- The gaseous state of water is known as water vapour. At 100o Celsius water reaches its boiling point and gets converted into water vapour.
Chemistry of Water
- It is a colourless and a tasteless liquid.
- Compared to other liquids, it has higher thermal conductivity, specific heat, surface tension, etc.
- Water is referred to as universal solvent as most substances such as acids, salts, sugar, and gases readily dissolve in it.
- Water has the capability to form azeotropes with other solvents.
- The electrical conductivity of water is low. However, it can be improved by adding ionic substances that dissociate to give ions in the aqueous phase for carrying the charge.
Learn more about the physical and chemical properties of water.
The water cycle, also known as the hydrologic cycle, is the continuous movement of water from the earth’s surface to the atmosphere and then back to the ground. It is a continuous process. Hence, it does not have a starting or an ending point. Thus, the water present on earth has been in circulation since the evolution of the earth.
Uses of Water
- Agriculture: The most important use of water is for agriculture. Irrigation is necessary for agriculture, and for that, water is the key component to produce food.
- Drinking: Human body contains 50% to 78% of water according to the size of the body. Humans need to drink 7 liters of water every day to avoid dehydration.
- Health: It plays an important role in digestion and other biological processes that occur in living organisms. It plays an important role in maintaining the pH of the body. It also helps in the movement of antibodies from the immune system.
- Regulator: It helps in regulating the body temperature. Water provides the necessary cooling effect on the body.
- Intoxication: Water removes harmful toxins from the body through perspiration and urination. It prevents the buildup of wastes in living organisms.
- Washing: It is used to make emulsions and solutions which are used for washing purposes.
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