What intermolecular forces are found in carbon disulfide, CS2?
a. Dipole-dipole forces
b. Dispersion forces
c. lon-dipole bonding
d. Hydrogen bonding
The Correct Answer and Explanation is:
The correct answer is b. Dispersion forces.
Explanation:
Carbon disulfide (CS₂) is a simple molecular compound consisting of carbon and sulfur atoms. To understand the intermolecular forces present in CS₂, we need to examine its molecular structure and polarity.
- Molecular Structure and Polarity:
CS₂ has a linear molecular geometry with carbon in the center and sulfur atoms at both ends. The carbon-sulfur bond is covalent, with sulfur being more electronegative than carbon, which would typically create a dipole moment. However, the linear shape of the molecule means that the individual bond dipoles cancel out. As a result, CS₂ is a nonpolar molecule. The absence of a permanent dipole moment indicates that CS₂ cannot exhibit dipole-dipole interactions (choice a), which occur between polar molecules. - Dispersion Forces:
Despite being nonpolar, CS₂ still experiences intermolecular forces due to the movement of electrons within the molecule. These forces are known as London dispersion forces (or simply dispersion forces). Dispersion forces arise because of temporary fluctuations in the electron distribution within atoms or molecules, which create instantaneous dipoles. These dipoles induce corresponding dipoles in nearby molecules, leading to attractive forces. Dispersion forces are present in all molecules, but they are the only intermolecular force in nonpolar molecules like CS₂. Thus, dispersion forces are the primary intermolecular force in CS₂, making option b the correct answer. - Other Intermolecular Forces:
- Ion-dipole bonding (choice c) occurs between ions and polar molecules, which is not relevant to CS₂, as it does not contain ions or a permanent dipole.
- Hydrogen bonding (choice d) requires a hydrogen atom bonded to a highly electronegative atom (such as nitrogen, oxygen, or fluorine), and CS₂ does not have such hydrogen bonds.
In conclusion, the primary intermolecular force in carbon disulfide is dispersion forces.