Read "the ozone hole" and answer the question below.

use examples from the article to explain one positive and one negative effect that chemistry has had on society.

Positive effect -  allow the search and development of environmental friendly sources, to decrease the risk of polluents in the ozone (in the world).

Negative effect - environmental imbalances like: toxic gas leaks, river and soil contamination, etc.

Explanation:

   Ozone (O3) is one of the gases that make up the atmosphere and about 90% of its molecules are concentrated between 20 and 35 km altitude, called the Ozone Layer. Its importance is that it is the only gas that filters out type B ultraviolet radiation (UV-B), which is harmful to living beings.  

  Ozone has different functions in the atmosphere depending on its altitude. In the stratosphere, ozone is created when solar ultraviolet radiation interacts with the oxygen molecule, breaking it into two oxygen atoms (O). The released oxygen atom attaches itself to an oxygen molecule (O2), thus forming ozone (O3). In the stratospheric region, 90% of type B ultraviolet radiation is absorbed by ozone.  At ground level in the troposphere, ozone loses its protective function and becomes a polluting gas, responsible for increasing surface temperature, together with carbon monoxide (CO), carbon dioxide (CO2), methane (CH4) and nitrous oxide.

  Several chemicals are destroying ozone. By reacting with it, the nitric and nitrous oxides expelled from vehicles and the CO2 produced by burning fossil fuels such as coal and oil are destroying the protective layer of the planet, opening holes in it.

  To reduce gas emissions, chemical professionals have been studying in depth the substitution of fossil energy, which generates a lot of pollution, by the so-called renewable energy. Other example can be the electric car, which is environmentally friendly because it does not emit polluting gases, is already a reality, sold in many countries. So, this a positive effect of chemistry nowadays, which it can allow the search for environmental friendly sources, to decrease the risk of polluents.

     But associated with progress, we have a multitude of environmental imbalances. Toxic gas leaks, river and soil contamination and poisoning by ingestion of contaminated food are problems shown daily - these could be some negative effects of chemistry nowadays.

samuel de champlain. in 1608, king henry iv sponsored pierre dugua, sieur de mons and samuel de champlain as founders of the city of quebec with 28 men. this was the second permanent french settlement in the colony of canada.

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