Problem 25 - A Complete Resource Book in Chemistry for JEE Main

Question

Westron, a good industrial solvent, is (a) acetylene tetrachloride (b) trichloroethylene (c) dichlorodifluoromethane (d) hexachlorocyclohexane

Step-by-Step Solution

Answer

The correct answer is (b) trichloroethylene.

Step 1: Identify the Nature of the Question

The question asks us to identify \( \text{Westron} \), which is described as a good industrial solvent. An industrial solvent is typically a chemical that can dissolve other substances.

Step 2: Analyze the Option

Examine each option given to find characteristics that match those of an industrial solvent. Consider the chemical and physical properties of each compound.

Step 3: Evaluate the Characteristics

- **Acetylene tetrachloride (a):** This is not commonly recognized as a standard industrial solvent. - **Trichloroethylene (b):** Known for being an effective industrial solvent, especially in degreasing metals. - **Dichlorodifluoromethane (c):** Mainly used as a refrigerant and not a typical solvent. - **Hexachlorocyclohexane (d):** Primarily used as an insecticide rather than a solvent.

Step 4: Conclusion

The correct choice, based on the properties and common use as an industrial solvent, is trichloroethylene, which is option (b). It is well-known for its effectiveness in industrial applications like degreasing metals.

Key Concepts

Trichloroethylene

Trichloroethylene, often abbreviated as TCE, is a chlorinated hydrocarbon used extensively in industrial settings. It is a volatile, dense liquid with a sweet, chloroform-like odor. Known for its adeptness in solvency, TCE is primarily employed for degreasing metals, thanks to its ability to dissolve oils and greases.
Other uses of TCE include:

• Production of hydrofluorocarbon (HFC) intermediates.
• Use in extraction processes in the pharmaceutical industry.
• Consumer product care, such as certain cleaning fluids.

Mentioning trichloroethylene often brings up concerns about its environmental and health impacts, leading to restricted use in various countries. However, its solvency power in industrial degreasing cannot be underestimated.

Chemical Properties

Understanding the chemical properties of trichloroethylene helps in predicting its behavior and usefulness as a solvent. Its chemical formula is C_2HCl_3, and it has a boiling point of 87°C (189°F). With a relatively high density of 1.46 g/cm³, it is heavier than water and tends to sink in aquatic environments.
The main chemical properties that make it an effective solvent include:

• High solvency power for non-polar substances like greases and oils.
• Volatility, allowing it to evaporate quickly after application, reducing residue.
• Non-inflammable, making it safer to handle compared to other volatile organic compounds.

These traits also imply certain safety measures needed during use, such as adequate ventilation and protective equipment to minimize exposure.

Solvent Identification

Identifying a solvent suitable for industrial use involves evaluating its ability to dissolve different substances effectively. The solvent's chemical properties, such as being non-polar or polar, come into play when determining what it can dissolve. Other factors include its evaporation rate, safety, and environmental impacts.
When identifying trichloroethylene as an industrial solvent, consider:

• Its high effectiveness in removing grease, oil, and wax.
• Its role as an intermediate in chemical manufacturing processes.
• Industry preferences for non-combustible options.

While trichloroethylene is ideal for metal degreasing, regulatory restrictions must also be considered due to its potential health risks, making proper handling and disposal crucial.