Chemistry 2010 JAMB Past Questions - Question 48: The haloalkanes used in the dry-cleaning industries are

Correct Answer

A

Explanation

The haloalkanes most commonly used in the dry-cleaning industry are **trichloroethene (C2HCl3) and tetrachloroethene (C2Cl4)**. Here's why the other options are not as widely used:

**Trichloromethane (CHCl3) and tetrachloromethane (CCl4):**

* **Trichloromethane:** Also known as chloroform, it was once widely used in dry cleaning but is now largely banned due to its health and environmental concerns.
* **Tetrachloromethane:** Also known as carbon tetrachloride, it was also commonly used in dry cleaning but is now restricted due to its toxicity and ozone depletion potential.

**Chloroethene (CH2=CHCl) and dichloroethene (C2H2Cl2):**

* These compounds are more reactive than trichloroethene and tetrachloroethene and can damage some fabrics. Additionally, they present potential health risks and are not commonly used in modern dry cleaning.

**Chloroethane (CH3CH2Cl) and dichloroethane (C2H4Cl2):**

* These compounds are even more reactive than chloroethene and dichloroethene, making them unsuitable for most dry cleaning applications. They are also volatile and flammable, posing safety concerns.

Therefore, while some of the other listed options have been used in dry cleaning historically, **trichloroethene and tetrachloroethene remain the most prevalent choices**, albeit with growing trends towards more environmentally friendly alternatives.