Carbon Tetrachloride
Definition and meaning of Carbon Tetrachloride in chemistry.
Carbon tetrachloride is a colorless, dense liquid compound in which four chlorine atoms are bonded tetrahedrally to a single carbon atom, formula CCl4. It was once a major industrial solvent and dry-cleaning agent but is now heavily restricted due to its toxicity and role in stratospheric ozone depletion.
In more detail
Although each C-Cl bond is polar, the molecule's symmetric tetrahedral geometry causes the four bond dipoles to cancel exactly, making carbon tetrachloride nonpolar overall. This nonpolarity lets it dissolve fats, oils, and other nonpolar substances readily, while it remains immiscible with water and sinks below it (density 1.59 g/mL). Because it is nonflammable, it was historically used in fire extinguishers and as a chemical feedstock for producing chlorofluorocarbons (CFCs). Its use has since been sharply curtailed after it was found to be hepatotoxic, a probable human carcinogen, and a potent ozone-depleting substance controlled under the Montreal Protocol.
Key facts
| Formula | CCl4 |
|---|---|
| Molar Mass | 153.81 g/mol |
| Boiling Point | 76.7 °C |
| Field | Organic Chemistry |
In the mid-20th century, carbon tetrachloride was sold as a "Pyrene" fire-extinguishing liquid because its dense, nonflammable vapor smothered small flames by displacing oxygen; this use was later abandoned once it was discovered that contact with flame converts CCl4 into toxic phosgene gas.
Frequently asked questions
Why is carbon tetrachloride nonpolar if its C-Cl bonds are polar?
Its four identical bonds point symmetrically toward the corners of a tetrahedron, so the individual bond dipole moments cancel vectorially, giving the molecule a net dipole moment of zero.
Why was carbon tetrachloride phased out of common use?
It causes liver damage, is classified as a probable human carcinogen, and depletes stratospheric ozone, so its production and use are now restricted under the Montreal Protocol and health and safety regulations.