Page 30 - Curriculum Visions Dynamic Book

Chlorine compounds as solvents
A solvent is a liquid chemical substance that will Degreasing agents
dissolve another solid substance and yet not react with it. Solvents can also be used
to extract one material from another.
Chlorine (and the other halogens), especially when combined with hydrocarbons, easily dissolves organic materials (grease, oil,
Solvents are widely used in engineering factories. Many machines use grease and oil as both a lubricant and coolant. As a result, components often have a thin film of oil or grease on them. This must be removed before they can be coated with
fat etc.). This makes them very useful solvents paint or other finish, a process
Chlorine Carbon
 A representation of trichloroethene.
for organic materials, because water, the
most common solvent, will not dissolve organic
materials. agent, often in combination
called degreasing. Trichloroethene is the
One of the most widely used chlorinated hydrocarbons is trichloroethene. It is used in “dry cleaning” (that is, cleaning without water and using some other liquid solvent instead).
The advantage of trichloroethene over other petroleum-based solvents such as turpentine is that it will not catch fire.
In the dry cleaning process, the solvent
is mixed with a detergent. At the end of the cleaning cycle the solvent is recovered from the machine for reuse.
most widely used degreasing with a detergent.
Hydrogen
Carbon tetrachloride
Carbon tetrachloride, like trichloroethene, has been widely used as a solvent for removing grease from fabrics. For many years carbon tetrachloride was available for use in the home – often in the form of a jar with a fabric applicator – as a “spot remover”.
It has subsequently been discovered that the fumes from carbon tetrachloride are a health hazard, and its sale is now restricted.
 A representation of carbon tetrachloride or tetrachloromethane.
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