The Bhopal Gas Tragedy

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Accidents due to Corrosion
The Bhopal gas tragedy (December 1984) :
The Bhopal gas tragedy occurred in December 1984 wherin approximately 41 tonnes of deadly MIC was released in the dead of night. Water carrying catalytic material had entered Methyl Isocynate storage tank No. 610. The killer gas spread throughout the city, sending residents scurrying through the dark streets. No alarm ever sounded a warning and no evacuation plan was ever prepared. When victims arrived at hospitals doctors did not know how to treat them. It caused death of over 3000 people and continued lifelong misery for over 300000 with certain genetics defect that passed on to the next generation.
At the UCC Bhopal Plant there had been numerous accidents before 1984 tragedy.
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Their general chemical structure is R-N=C=O. Methyl isocyanate (CH3-N=C=O) is a monoisocyanate (in this case, R is CH3). The existence of adjacent double bonds confers high reactivity to isocyanates by a cumulative action. That is why MIC is very toxic. All isocyanates are toxic, and their toxicity is greater following inhalation than following oral ingestion. MIC is the most toxic member of the isocyanate family. At room temperature, MIC is a colorless liquid. MIC is flammable; its molecular mass is 57.05, specific gravity 0.96 relative to water at 20°C, vapour pressure 348 mm Hg (464 mbar) at 20°C and vapour density 1.97 relative to air. The boiling point of MIC is 39.1°C, which implies that some MIC will vaporize at a room temperature of 23°C and all of it can exist as vapor in Bhopal on certain hot days of the summer. Because MIC is odorless, contact with it is noted only because of toxicity.The Occupational Safety and Health Administration in the United States has set exposure limits to MIC as0.02 ppm (or 0.05 mg/m3) during an…show more content…
Petroleum coke (2C) was reacted with oxygen to produce 2CO.
2. CO and chlorine were reacted to produce phosgene (COCl2).
3. Phosgene and methylamine (CH3NH2) were reacted to produce methylcarbamoyl chloride (CH3NHCOCl) plus HCl.
4. Methylcarbamoyl chloride was then pyrolyzed to yield MIC (CH3NCO) and HCl.
5. In the last step, MIC was reacted with a slight excess of O-naphthol in the presence of a catalyst in carbon tetrachloride solvent to produce cabaryl.
Reasons that led to such an disaster
The Leak:-
Reaction of MIC with water generates heat far above its boiling point. During the cleaning operation in the night of December 2, 1984, a small quantity of water went through the pipe into the MIC Tank 610. The heat generated by the reaction between water and MIC transformed liquid MIC into gas. The pressure became sufficiently high, rupturing the disc, and MIC spewed through the vent into the atmosphere. There is little substance to the UCIL claim that the accident was a result of sabotage by some disgruntled

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