Carbon tetrachloride, CCl4, is a unique organic compound. Although inert, it tends to participate in several reactions. The reactivity of CCl4 can be traced to its polarity which is the major discussion in this article.
Carbon tetrachloride (CCl4) is a colorless liquid with a sweet odor. It is an inorganic compound that is non-flammable and has a tetrahedral geometry. CCl4 is a good solvent for oils and fats and as a refrigerant.
These properties of CCl4, however, do not provide a detailed understanding of its reactivity. In this article, you will get a better understanding of CCl4 and its reactions.
About CCl4
Carbon tetrachloride (CCl4) is a colorless liquid with a sweet odor. It is an inorganic compound that is non-flammable and has a tetrahedral geometry.
CCl4 is a covalent compound. Four chlorine atoms share electrons with the four valence electrons of carbon, resulting in full outer shells for all five atoms. The bond between carbon and chlorine is covalent since the atoms in the compound share electrons.
CCl4 is soluble in alcohol, ether, chloroform, benzene, naphtha, CS2, and formic acid. It has a melting point of CCl4 is −9.3°F (−22.92°C) while its boiling point is 170.1°F (76.72°C).
What is the polarity of CCl4?
CCl4 is a non-polar molecule due to its symmetry. The dipole moment generated by four C-Cl bonds cancel out each other, resulting in a net zero dipole moment.
The polarity of a molecule is determined by the distribution of electrons in the molecule. A molecule is polar if it has an uneven distribution of electrons, resulting in a net dipole moment. On the other hand, a molecule is non-polar if it has an even distribution of electrons, resulting in a net zero dipole moment.
Carbon tetrachloride consists of a central carbon atom bonded to four chlorine atoms. The molecule has a tetrahedral geometry, with the chlorine atoms arranged symmetrically around the central carbon.
Each C-Cl bond is polar due to the difference in electronegativity between carbon (2.55) and chlorine (3.16). However, the overall molecule remains nonpolar.
Why? The symmetry of the tetrahedral shape ensures that the individual bond dipoles cancel out. In other words, the partial positive and partial negative charges from the C-Cl bonds balance each other, resulting in no net dipole moment.
The bond dipoles generated by the four C-Cl bonds are equal in magnitude but opposite in direction, resulting in a net zero dipole moment.
Is CCl4 an ionic or covalent molecule?
CCl4 is a covalent compound. Covalent compounds form when two or more non-metals share electrons to form a bond. In the case of CCl4, the carbon atom shares its valence electrons with the chlorine atoms to form four covalent bonds.
Implications of the nonpolar nature of CCl4
Solubility
CCl4 is an excellent solvent for nonpolar compounds. Its nonpolar nature allows it to dissolve substances like fats, oils, and hydrocarbons.
Despite its liquid state, CCl4 is insoluble in water due to the lack of attractive forces between nonpolar CCl4 molecules and polar water molecules. However, it dissolves in non-polar solvents like alcohol, ether, formic acid, chloroform, and benzene.
Lack of hydrogen bonding
Hydrogen bonding, a strong intermolecular force, occurs in polar molecules. Since CCl4 is nonpolar, it does not participate in hydrogen bonding.
Overall, CCl4’s nonpolar nature affects its solubility and interactions with other molecules.
How does the polarity of CCl4 affect its reactions?
Since CCl4 is a non-polar molecule, it is not very reactive. It is not easily attacked by nucleophiles or electrophiles. However, it can undergo substitution reactions with halogens, such as chlorine and bromine, to form CCl3X and CCl2X2, respectively.
Some reactions of CCl4 are as follows:
Reaction with phosphoric anhydride
CCl4 reacts with phosphoric anhydride (P2O5) to yield phosgene (COCl2) and phosphoryl chloride (POCl3):
3CCl4 + P2O5 → 3COCl2 + 2POCl3
Reaction with dry zinc oxide
At 200°C, CCl4 reacts with dry zinc oxide (ZnO) to yield zinc chloride (ZnCl2), phosgene (COCl2), and carbon dioxide (CO2):
3CCl4 + ZnO → ZnCl2 + COCl2 + CO2
Formation of chloroform (CHCl3)
CCl4 can react with chlorine (Cl2) in the presence of sunlight to form chloroform (CHCl3):
CCl4+ Cl2 → (sunlight) CHCl3 + HCl
Reaction with sodium hydroxide (NaOH)
Carbon tetrachloride reacts with sodium hydroxide (NaOH) to form sodium chloride (NaCl) and sodium hypochlorite (NaClO):
CCl4 + 4NaOH → NaCl + NaClO+ 2H2O
CCl4 participates in various reactions, forming different products based on the reactants involved. Its nonpolar nature influences these reactions, making it a versatile compound in chemical processes.
FAQs
Why is NH3 polar, and CCl4 not polar?
NH3 is polar because its shape is uneven, forming a trigonal pyramidal structure. CCl4, however, is nonpolar despite its polar C-Cl bonds. The symmetrical tetrahedral structure cancels out the bond polarity.
The unequal distribution of charges in ammonia due to the different electronegativities of nitrogen and hydrogen creates a net dipole moment.
Is CCl4 harmful to the environment?
Yes, CCl4 is harmful to the environment due to its ozone-depleting properties. Its use has been restricted to prevent environmental damage.
Why is CCl4 highly soluble in n-hexane, but insoluble in water?
CCl4 is nonpolar, like n-hexane, a nonpolar solvent. Nonpolar solutes dissolve in nonpolar solvents, making CCl4 highly soluble in n-hexane. In contrast, water is polar, and CCl4 being nonpolar results in insolubility.
Can CCl4 undergo combustion reactions?
No, CCl4 is not combustible. Its lack of hydrogen atoms makes combustion impossible.
Why does CCl4 have a higher boiling point than CHCl3 despite being nonpolar?
CCl4 has a higher boiling point due to extensive dispersion forces, overpowering the pd-pd interactions in CHCl3. Although CHCl3 is a polar compound, the increase in mass in CCl4 outweighs the impact of polarity, influencing the boiling point.
Conclusion
CCl4 is a non-polar covalent compound with a tetrahedral geometry. It dissolves in water due to the formation of hydrogen bonds between the water molecules and the chlorine atoms of CCl4. The polarity of CCl4 affects its reactions in water.
Since CCl4 is a non-polar molecule, it is not very reactive. However, it can undergo substitution reactions with halogens, such as chlorine and bromine, to form CCl3X and CCl2X2, respectively.
The reaction occurs because the halogens are more electronegative than carbon, making the carbon atom slightly positive and susceptible to attack by the halogen.
Although, CCl4 dissolves in non-polar solvents like iodine, while in a liquid state, it exhibits almost no solubility in water because nonpolar CCl4 molecules lack attractive forces with the polar water molecules.
You can also learn about the polarity of ammonia (NH3), a popular laboratory gas.