Problem 121 - A Complete Resource Book in Chemistry for JEE Main

Question

An insecticide SEVIN is made by the reaction of 1 - naphthol with methyl isocyanate. A union carbide plant in Bhopal, India, were using this process to make SEVIN for use as an agricultural insecticide. On December 3,1984 , either by accident or by sabotage, a value was opened that admitted water to a large tank of methyl isocyanate. The pressure and temperature within the tank rose very high and the pressure relief value opened to prevent the tank from bursting. A large quantity of methyl isocyanate rushed through the pressure relief valves and the vapours flowed with the breeze into populated areas, killing about 2500 people and injuring many more. The temperature rise in the tank was attributed to (a) Dissolution of \(\mathrm{CH}_{3}-\mathrm{N}=\mathrm{C}=\mathrm{O}\) in water (b) Dissolution of \(\mathrm{CH}_{3} \mathrm{NH}_{2}\) in water. (c) Dissolution of \(\mathrm{NH}_{3}\) in water. (d) Dissolution of \(\mathrm{CO}_{2}\) in water.

Step-by-Step Solution

Answer

(a) Dissolution of \(\mathrm{CH}_3\text{N}=\text{C}=\text{O}\) in water.

Step 1: Identify the Reactants

The reaction involves water ( ext{H}_2 ext{O}) and methyl isocyanate ( ext{CH}_3 ext{N}= ext{C}= ext{O}) as the primary substances interacting in the scenario.

Step 2: Analyze the Options

Examine each option to determine which dissolution would result in a temperature rise. Options include the dissolution of methyl isocyanate ( ext{CH}_3 ext{N}= ext{C}= ext{O}), methylamine ( ext{CH}_3 ext{NH}_2), ammonia ( ext{NH}_3), and carbon dioxide ( ext{CO}_2).

Step 3: Consider the Chemical Reactions

Consider that the dissolution of methyl isocyanate in water is exothermic, meaning it releases heat, causing the temperature and pressure to rise.

Step 4: Identify the Correct Reaction

The dissolution of methyl isocyanate ( ext{CH}_3 ext{N}= ext{C}= ext{O}) is the primary cause of the temperature increase because it is a highly reactive and exothermic reaction.

Step 5: Conclude the Cause

Given the context and chemical behavior, the correct cause of the temperature rise is the dissolution of methyl isocyanate ( ext{CH}_3 ext{N}= ext{C}= ext{O}) in water.

Key Concepts

Exothermic Reactions

Exothermic reactions are chemical reactions that release energy in the form of heat. This means that during the reaction, the products have less energy than the reactants, and the excess energy is given off, usually as heat. These reactions are often characterized by a rise in temperature of the reaction mixture. Think of a campfire: as the wood burns, it releases heat and light. Similarly, in chemical processes, when substances like methyl isocyanate mix with water, the reaction releases heat. This heat release is what makes exothermic reactions so significant in industrial settings. In the Bhopal incident, the exothermic nature of the reaction between water and methyl isocyanate led to a dramatic rise in temperature within the storage tank. This temperature increase heightened the pressure inside the tank, contributing to the catastrophic release of toxic gases that followed.

Methyl Isocyanate

Methyl isocyanate, abbreviated as MIC, is a highly reactive chemical compound with the formula \( \text{CH}_3\text{N}=\text{C}=\text{O} \). It's a key ingredient in manufacturing certain pesticides, like SEVIN. However, methyl isocyanate is also volatile and highly toxic.When it comes into contact with water, it reacts rapidly, releasing heat in an exothermic reaction. This high reactivity and the potential for releasing harmful gases mean that handling methyl isocyanate requires careful safety measures.Industries that utilize methyl isocyanate have strict protocols to minimize risk, such as controlling its exposure to moisture and maintaining proper storage conditions to avoid accidental chemical reactions. Despite these precautions, accidents can and have happened, highlighting the need for stringent safety standards.

Chemical Accidents

Chemical accidents refer to unintentional releases of hazardous substances, leading to potential harm to people and the environment. These can occur due to a variety of factors, like equipment failure, human error, or sabotage, as speculated in the Bhopal disaster. The Bhopal chemical disaster is one of the most well-known industrial catastrophes involving chemical release. Here, the accidental introduction of water into a tank of methyl isocyanate led to the massive release of toxic gases. Chemical accidents emphasize the importance of:

• Regular maintenance and inspection of industrial equipment.
• Comprehensive training for all personnel handling hazardous substances.
• Emergency response protocols to minimize impact.

Learning from past incidents is crucial for preventing future accidents and ensuring public safety.

Industrial Chemistry

Industrial chemistry involves the large-scale application of chemical processes for manufacturing a wide range of products, from pharmaceuticals to fertilizers. While it advances numerous fields and drives economic growth, it also comes with significant responsibility, especially regarding safety. Safety in industrial chemistry is paramount due to the aggressive nature of many chemicals involved. Companies must rigorously monitor reactions, use appropriate containment equipment, and ensure that workers understand proper handling procedures. In the context of the Bhopal disaster, it illustrates the risks of industrial chemistry when safety protocols fail or are inadequate. The event stresses the need for industries to:

• Implement strict safety regulations.
• Regularly improve risk assessments.
• Invest in technology that can prevent or minimize exposure to hazardous substances.

Collectively, these measures can help to create a safer environment in industrial chemical applications.