Which of the following have the strongest intermolecular forces?
A. CH3Cl
B. CHCl3
C. CCl4
D. CH4
The correct answer and explanation is:
The correct answer is B. CHCl3 (Chloroform).
To understand why CHCl3 has the strongest intermolecular forces, let’s examine the properties of each compound.
A. CH3Cl (Methyl chloride) is a polar molecule due to the difference in electronegativity between carbon, hydrogen, and chlorine. It experiences dipole-dipole interactions and London dispersion forces. However, these forces are not as strong compared to those in CHCl3.
B. CHCl3 (Chloroform) is also a polar molecule, but it has a higher polarity than CH3Cl due to the three chlorine atoms, which are more electronegative than hydrogen. This greater electronegativity creates stronger dipole-dipole interactions. In addition to dipole-dipole forces, CHCl3 experiences hydrogen bonding due to the presence of hydrogen atoms attached to a highly electronegative atom (chlorine). This combination of forces gives CHCl3 the strongest intermolecular interactions.
C. CCl4 (Carbon tetrachloride) is a nonpolar molecule, even though it contains chlorine atoms. The symmetry of the molecule cancels out any dipole moment, and thus, CCl4 only experiences London dispersion forces. These forces are generally weaker than dipole-dipole interactions and hydrogen bonding, so CCl4 has the weakest intermolecular forces among the options.
D. CH4 (Methane) is a nonpolar molecule, and like CCl4, it only experiences London dispersion forces, which are the weakest type of intermolecular force. Methane has the weakest intermolecular forces of all the compounds listed.
Thus, CHCl3 has the strongest intermolecular forces due to its polarity and the ability to form hydrogen bonds, making it the correct choice.