Study Guides/Chemistry/Carbon Tetrachloride Formula
Study Guide · Chemistry

Carbon Tetrachloride (CCl4) — Formula and Properties

Carbon Tetrachloride is a clear, colorless, and highly volatile liquid with a sweet odor that smells slightly like chloroform. It was historically used in fire extinguishers and as a cleaning fluid, but its use is now heavily restricted due to its extreme toxicity.

Question (Click to Flip)

What happens if you use CCl4 to put out a fire today?

Answer

It is extremely dangerous. When carbon tetrachloride is exposed to high heat (like a fire), it reacts with the oxygen in the air to form Phosgene gas (COCl₂), which is a highly lethal chemical weapon used in World War I.

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Key Facts

Because CCl₄ is non-polar, it does not dissolve in water (which is polar). If you mix CCl₄ and water in a beaker, they will separate into two distinct layers, with the heavier CCl₄ sinking to the bottom.

The Chemical Formula

The chemical formula for carbon tetrachloride is CCl₄.

Breaking down the name:

  • Carbon: One atom of Carbon (C).
  • Tetra: A prefix meaning 'four'.
  • Chloride: Four atoms of Chlorine (Cl).

Other chemical names for it include Tetrachloromethane (IUPAC name), Halon-104, and Freon-10.

Structure and Bonding

Carbon has 4 valence electrons, and it needs 4 more to complete its octet. Chlorine has 7 valence electrons and needs 1 more.

Therefore, one central Carbon atom forms four single covalent bonds with four Chlorine atoms.

Because the four chlorine atoms mutually repel each other equally, they spread out as far away from each other as possible, giving CCl₄ a perfect 3D Tetrahedral geometry with bond angles of exactly 109.5°.

Is CCl4 Polar or Non-Polar?

This is a classic chemistry exam question.

Even though the C-Cl bonds themselves are highly polar (because Chlorine is much more electronegative than Carbon and pulls the electrons towards itself), the CCl₄ molecule as a whole is NON-POLAR.

Why? Because of its perfectly symmetrical tetrahedral shape. The four chlorine atoms pull the electrons equally in exactly opposite directions. The polarities cancel each other out completely, resulting in a net dipole moment of zero.

Uses and Toxicity

  • Historical Uses: It was famous as a dry cleaning solvent, a refrigerant, and was pumped into early fire extinguishers because it is non-flammable.
  • Current Status: CCl₄ is highly toxic to the liver and kidneys. More importantly, it is a severe ozone-depleting substance. Under the Montreal Protocol, its production and use for general purposes have been globally banned.

Questions and Answers

What happens if you use CCl4 to put out a fire today?+

It is extremely dangerous. When carbon tetrachloride is exposed to high heat (like a fire), it reacts with the oxygen in the air to form **Phosgene gas** (COCl₂), which is a highly lethal chemical weapon used in World War I.

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