Question

Which of Cl_2 or I_2 has the higher boiling point and why?

A. Cl_2 because it has the higher molar mass, and, therefore, stronger dispersion forces.
B. I_2 because it has less molar mass, and, therefore, less dispersion forces.
C. Cl_2 because it has less molar mass, and, therefore, stronger dispersion forces.
D. I_2 because it has higher molar mass, and, therefore, stronger dispersion forces.

Answer 1

Iodine (I2) has a higher boiling point than Chlorine (Cl2) because it has a higher molar mass, leading to stronger dispersion forces that require more energy to overcome.

Step-by-step explanation:

The boiling point of a substance is related to the strength of the intermolecular forces present in that substance. Among the halogens, I2 has a higher boiling point than Cl2 due to I2's higher molar mass, which leads to stronger dispersion forces. As a result, I2 requires more energy to overcome these forces and transition from a liquid to a gas compared to Cl2, which has a lower molar mass and therefore weaker dispersion forces. For this reason, the correct answer is D. I2 because it has higher molar mass, and, therefore, stronger dispersion forces.

ICI. ICl and Br₂ have similar masses (~160 amu) and therefore experience similar London dispersion forces. IC1 is polar and thus also exhibits dipole-dipole attractions; Br₂ is nonpolar and does not. The relatively stronger dipole-dipole attractions require more energy to overcome, so ICI will have the higher boiling point.