Green Chemistry is to avoid environmental pollution. Explain.

Explanation

The ways of using the knowledge and the principles of chemistry and other sciences to develop methods to reduce the pollution of the environment as far as possible are known as green chemistry.
The over exploitation of the soil using fertillisers and pesticides polluted the soil, water and air. But farming, irrigation etc. cannot be stopped. Then, methods to reduce the environmental pollution must be developed.
Generally in a reaction some by- products are formed. In many processes these by-products become the pollutants. Green chemistry works for not producing wasteful by-products in these processes.
Normal process:
`{:(" "A" "+" "B " "to" " dotC" "+" "D...........(1)),(" Reactant "" Reactant "" "Product " "" Wasteby-product "):}`
According to green chemistry the process shall be
`{:(" "A" "+" "B " "to" " C" "...........(2)),(" Reactant "" Reactant "" "Product " "):}`
As the reaction (2) gives no by-product it is called an environmental-friendly reaction. Even if a by-product is formed, it must be made a useful product instead of polluting the environment. Green chemistry suggests that instead of using conventional fuels and energy systems, non-conventional fuels and non-conventional systems must be put into practice. Because of this, pollution would be reduced.
Green chemistry is a cost effective approach that involves minimum chemical usage, minimum energy consumption and minimum waste (pollutant) generation.
Ex : In the dry cleaning of clothes, tetrachloroethane was used earlier. This compound contaminates the ground water. Therefore, this compound is replaced by liquified `CO_2` along with a suitable detergent. This would not pollute ground water much. Nowadays, `H_2O_2` is used for bleaching clothes in laundries. This gives better results and decreases the consumption of water.