Notes On Green Chemistry - CBSE Class 11 Chemistry
The earth's atmosphere along with its soil and water is polluted every day. And it is not possible to eliminate the causes of pollution, such as industries and vehicles, all at once. It is possible to find alternate production methods that would not pollute the environment as much as the current methods. The branch of chemistry that deals with the research and discovery of such methods is known as green chemistry. It uses existing scientific knowledge to help find environment-friendly and cost-effective production methods. It suggests that industries use chemical reactants that yield optimum products and minimum waste as combating the environmental impact of these chemicals is a costly venture in terms of time, energy and money. It emphasizes the prevention of harmful chemical impact through a chemical process that involves decreasing the amounts of harmful chemicals to achieve zero discharge of pollutants and emissions. If the reactants in a chemical reaction are completely converted into environment-friendly products through an environment-friendly medium, then there would be zero discharge of pollutants. Synthetic reactions can be carried out in an aqueous medium as water is cost-effective, non-inflammable and free from carcinogenic effects. For dry cleaning of clothes, earlier tetrachloroethene was used; a suspected carcinogen that also contaminates ground water. This process has now been replaced by a process of using liquefied carbon dioxide with a detergent that results in less harm to ground water. Nowadays, hydrogen peroxide is used for bleaching in the process of laundry as it gives a better result with the use of less water. In chemical synthesis, ethanal is now prepared by one-step oxidation of ethene in an aqueous medium in the presence of an ionic catalyst.                                                   Catalyst CH2=CH2 +O2                $\stackrel{\to }{\frac{\text{Pd(II)}}{\text{Cu(II)}}\text{(in water)}}$              CH3CHO(90%) This gives a yield of 90%. In 2005, Yves Chauvin, Robert H. Grubbs and Richard R. won the Nobel Prize for chemistry for work that reduces hazardous waste in creating new chemicals.

#### Summary

The earth's atmosphere along with its soil and water is polluted every day. And it is not possible to eliminate the causes of pollution, such as industries and vehicles, all at once. It is possible to find alternate production methods that would not pollute the environment as much as the current methods. The branch of chemistry that deals with the research and discovery of such methods is known as green chemistry. It uses existing scientific knowledge to help find environment-friendly and cost-effective production methods. It suggests that industries use chemical reactants that yield optimum products and minimum waste as combating the environmental impact of these chemicals is a costly venture in terms of time, energy and money. It emphasizes the prevention of harmful chemical impact through a chemical process that involves decreasing the amounts of harmful chemicals to achieve zero discharge of pollutants and emissions. If the reactants in a chemical reaction are completely converted into environment-friendly products through an environment-friendly medium, then there would be zero discharge of pollutants. Synthetic reactions can be carried out in an aqueous medium as water is cost-effective, non-inflammable and free from carcinogenic effects. For dry cleaning of clothes, earlier tetrachloroethene was used; a suspected carcinogen that also contaminates ground water. This process has now been replaced by a process of using liquefied carbon dioxide with a detergent that results in less harm to ground water. Nowadays, hydrogen peroxide is used for bleaching in the process of laundry as it gives a better result with the use of less water. In chemical synthesis, ethanal is now prepared by one-step oxidation of ethene in an aqueous medium in the presence of an ionic catalyst.                                                   Catalyst CH2=CH2 +O2                $\stackrel{\to }{\frac{\text{Pd(II)}}{\text{Cu(II)}}\text{(in water)}}$              CH3CHO(90%) This gives a yield of 90%. In 2005, Yves Chauvin, Robert H. Grubbs and Richard R. won the Nobel Prize for chemistry for work that reduces hazardous waste in creating new chemicals.

Previous
Next