Final answer:
To determine intermolecular force strength, consider the types of forces, molar mass, and surface area. Larger molecules with more electrons tend to have stronger London Dispersion Forces. Substances with weaker intermolecular forces have lower boiling points.
Step-by-step explanation:
To determine which molecule has higher or lower intermolecular forces (IMFs), one must consider the types of IMFs present and the size of the molecules. London Dispersion Forces (LDFs), a type of Van der Waals force, are typically found in all molecules, especially in nonpolar ones. Larger molecules exhibit greater LDFs due to increased polarizability, which arises because they have more electrons that are further away from the nucleus.
When comparing molecules, if they exhibit similar types of IMFs, you can look at their molar masses and surface area. Higher molar mass and greater surface area tend to correspond to stronger IMFs. Additionally, the potential energy graph can be used; a higher potential energy indicates stronger intermolecular interactions. Hence, substances that have weaker forces and lower molar masses usually have lower boiling points since it takes less energy to overcome their IMFs.