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The Worst Ever Chemical Hazard: Bhopal Catastrophe.
By now, Union Carbide Limited is nowhere, but similar situations are still threatening
“Bhopal” is a city situated in the state of “Madhya Pradesh” In India. In the year of 1984, a multi national company namely, “Union Carbide India Limited”, was operating its business in India through a manufacturing plant at Bhopal.
This plant of the company was engaged in manufacturing poisonous chemicals called pesticides and insecticides. These are the chemicals which are used to kill pests and insects present in agricultural farms. In these way such chemicals are useful to protect our crops.
One of the most poisonous chemicals being manufactured in this plant was, “Methyl Isocyanate”, abbreviated as, “M. I. C. gas”.
The entire incident is focused on this chemical: M. I. C. gas.
On 3rd December 1984, leakage of a poisonous M. I. C. gas took place in Bhopal.
Soon, a particular area of Bhopal city was covered under the blanket of this poisonous gas.
Due to hazardous effect of this gas, as much as about three thousand and seven hundred (3700) people died in Bhopal, and many more suffered serious health problems.
Two methods to prepare Methyl Isocyanate
Methyl isocyanate can be prepared by either of the following two methods.
(1) It can be prepared by oxidation of methyl isocyanide. In this method chemical reaction takes place between methyl isocyanide (CH3NC) and mild oxidizing agent mercuric oxide (HgO).
(2) It can also be prepared by reaction between methyl amine & phosgene.
See the following picture showing equations of above two reactions.
Picture showing equations to prepare M. I.C.
Chemical characteristics of “M. I. C."
“M. I. C. gas” is scientific name of the chemical compound, “METHYL ISOCYANATE”.
The chemical formula of this dangerous compound is: “CH3N=C=O”.
Actually it is not a gas but a volatile liquid having boiling point to be 390 C (means 102.20 F or 312 K). Due to low boiling point, it readily gets evaporated and converted into its vapor which is called, “M. I. C. GAS”.
Due to cumulative (means adjacent) double bond system present, M. I. C. is extremely reactive.
It is also toxic to human being because it vigorously reacts with:
(a) hydroxy (-OH) group,
(b) amino (-NH2) group and
(c) Thioalcohol or thiol (SH) functional group.
Compounds containing all these functional groups are present in our body in the form of:
(2) proteins and
Horrible effects of M. I. C. on Human Body
How M. I. C. destroyed lives?
Due to above two characteristics, when M.I. C. gas come into contact with body, it is readily absorbed by the skin, and starts chemical reactions to cause:
(a) It causes blisters on that part of skin which is in contact with it. This results in complete destruction of skin in contact with M. I. C. and
(b) It causes damage to the lung tissues. This results in serious breathing problems.
Can you imagine agony of a person or a child with blisters on skin, eyes, nose, trachea (windpipe) and every where on his/her body?
Don't imagine, even imagination will hurt you!
Why Union Carbide Was Manufacturing MIC?
Commercial use of M. I. C.:
With the growing needs of agricultural products, the use of pesticides has also increased extensively.
All pesticides are poisonous? Yes, definitely, because then only it can destroy pests!
Sevin is one of such poisonous pesticide!
In Union Carbide (India) Limited, the M. I. C. gas was manufactured and used in order to prepare an insecticide (a chemical which kills insects) called, “Carbaryl”.
The scientific name of carbaryl is: "1-Napthyl-N-methylcarbamate" and its commercial name is, “Sevin”.
Sevin is prepared by chemical reaction between M. I. C. & 1-Napthol.
This is shown in the following figure.
Use of Sevin:
Sevin is very poisonous compound. It is used in agriculture to destroy the unwanted and harmful pests and insects present in agricultural plants.
Picture Showing Structure and Preparation of Dangerous Pesticide, "Sevin"
Phosgene-Another Hazard Available With Company
It was not only M. I. C. which can threat lives of people. There was also another hazard with the company which can kill people. The name of this hazard is, "Phosgene". It is also fatal.
The poisonous effects of phosgene were so deadly that during world war, it was used as a war gas.
In old times its fatal effects claimed many lives. This happened due to its accidental presence in chloroform which was used as anesthesia . In presence of sunlight, chloroform can react with oxygen to produce phosgene as per following equation:
CHCl3 + [O] + sunlight → COCl2 + HCl.
It was due to this reason that chloroform used for anesthetic purpose was stored in a dark colored air-tight bottle and was tested before using.
Picture showing structure of dangerous compound Phosgene
This is the chemical reaction, which claimed 3700 lives
What happened that night which resulted in leakage of M. I. C.?
Did a pipe carrying poisonous gas ruptured? Did a vessel exploded? Did a lid of container containing poisonous gas was remained open resulting in gas leakage? Did somebody play a mischief?
None of the above theories could convince the investigation team to conclude the true reason of leakage of M. I. C.
It was really shocking to know the true reason of massacre.
It was a chemical reaction responsible for tragedy!
The reaction was this:
CH3N=C=O + H2O → CH3NH2 + CO2.
Water is villain!
The above chemical reaction is highly exothermic resulted in overheating of vessel containing M. I. C.
Further it produced carbon dioxide gas resulting in increase in pressure inside the container.
The simultaneous effects of:
(1) Heating and
(2) Increase in pressure
resulted in blast of vessel containing M. I. C.!
As M. I. C. is a volatile liquid, soon it started to become a gas and with the help of wind, it started diffusing towards the city Bhopal.
What is called, “Volatile” and “Nonvolatile” Liquid?
Volatile liquid: The liquid that readily evaporates and gets converted into its vapor at room temperature, is called volatile liquid.
For example, petrol when kept open in the atmosphere, it readily evaporates into its vapor. Hence petrol is a volatile liquid.
Other examples are: ethanol, ether, water, etc.
Non-volatile liquid: The liquid that does not readily evaporates and gets converted into its vapor at room temperature, is called non volatile liquid.
For example, ground nut oil.
Other examples are: mercury, vegetable oil etc.
M. I. C. is not a gas, but is a volatile liquid.
Beginning of Catastrophe
In the early hours of Dec-3 (means after 12 o'clock of midnight of Dec-2), 1984, an underground storage tank of M. I. C., in the plant of union carbide limited, started leaking due to reason explained above.
Several tons of M. I. C. escaped this night and mixed with the atmospheric air. Due to direction of wind towards the city, it started moving towards Bhopal city.
Within short period of time, it diffused in the sky of Bhopal and covered a particular area of city below which several million people were sleeping.
As the density of M. I. C. vapors is about double to that of atmospheric air, M. I. C. vapors started settling down near ground, instead of diffusing into the air.
Due to its accumulation on the ground and also around residential units, it became impossible for the people below its cloud to escape.
People were arrested by M. I. C.!
It is true and well accepted conclusion that due to accidental reaction between M. I. C. and water, the entire massacre occurred.
However, it is still not known that how water entered into the vessels containing M. I. C.?
(a) Indian government alleged that:
Due to carelessness on the part of company, water entered into the vessel leading to explosion followed by leakage.
(b) However, company defended herself arguing that:
Due care was taken and M. I. C. was stored in airtight underground tank, where there was no possibility of entry for water. As per company sources, due to some sabotage the accident took place.
The actual reason, "How water entered?" is still not known!
True Homage To Victims
Tragedy is old.
what can we do now?
How can we pay a true homage to all the victims of Bhopal?
Yes, by assuring safe tomorrow to our future generation!
By following two promises:
(A) Assuring strict watch by the authority on all such manufacturing units.
In every country, there is a law to provide safety to her people.
The authorities and departments like:
(a) Industrial safety department
(b) Pollution control department
(c) Labor welfare department etc.
are supposed to take necessary action so that such incidents can be avoided.
Proper care must be taken to ensure that, various departments appointed such, are functioning properly.
Even though there are some laws in practice to protect people, due to non-transparency, they become ineffective and even ridiculous.
What to expect from authority?
Sample of surrounding air and ground water must be collected and analysed periodically and analytical results should be put forward to the public.
A strict law should be made to punish the corrupt officials.
(B) Applying green chemistry.
What is green chemistry?
It is about some alternate:
(a) raw material
(b) chemical reactions
(c) products and
which may be used in place of existing ones. This can ensure minimum chemical hazards.
This will help to provide safer tomorrow to our future generation.
How Safe it is to Eat the Apple?
How safe it is to use farm fresh fruits and vegetables?
The vegetables and fruits we use in our day to day life may contain dangerous chemicals like Sevin!
It is therefore necessary not to just wash them, but wash them thoroughly before using.
Even traces of poisonous chemicals can start new unwanted reactions in the body. Such chemicals may be even carcinogen which may induce Cancer in our body!
Wash all fruits and vegetables carefully before using them.
Eating Apple? Caution!
Is this article successful?
This article is successful only if:
Now on wards,
whenever you start eating an apple,
and see some spots on its surface,
suddenly an idea clicks in your mind that there may be some poisonous pesticides,
and you rush to wash it again,
This article is successful!
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