Question

As the molar mass increases, the (weaker/stronger) the dispersion forces. Why?

A) Weaker; smaller surface area
B) Stronger; larger surface area
C) Weaker; larger surface area
D) Stronger; smaller surface area

Answer 1

As the molar mass of a molecule increases, the dispersion forces become stronger due to a larger surface area and increased polarizability.

Step-by-step explanation:

The student asked how molar mass affects dispersion forces. As the molar mass increases, the stronger the dispersion forces. This is because larger molecules have a larger surface area, and consequently, they have more electrons in their electron cloud, which increases polarizability. As the number of electrons in the atoms or nonpolar molecules increases, the strength of dispersion forces also increases. The more polarizable a molecule is, the larger its dispersion forces will be. Therefore, the answer is B) Stronger; larger surface area.