Which of the following is a false statement about dispersion forces?

• A. Dispersion forces are the result of fluctuations in the electron distribution within molecules or atoms.
• B. Dispersion forces are present in all atoms and molecules.
• C. Dispersion forces result from the formation of instantaneous dipoles in a molecule or atom.
• D. Dispersion forces always have a greater magnitude in molecules with a greater molar mass.
• E. Dispersion force magnitude depends on the amount of surface area available for interactions.

Answer: (D)

Verified step by step guidance

1. Understand that dispersion forces, also known as London dispersion forces, are a type of van der Waals force that arise due to temporary fluctuations in electron distribution within atoms or molecules, leading to the formation of instantaneous dipoles.
2. Recognize that dispersion forces are indeed present in all atoms and molecules, as they are a fundamental aspect of intermolecular interactions, regardless of the presence of permanent dipoles.
3. Acknowledge that the magnitude of dispersion forces is influenced by the polarizability of the molecule, which is related to the ease with which the electron cloud can be distorted. Larger atoms or molecules with more electrons tend to have greater polarizability.
4. Consider that while dispersion forces generally increase with molar mass due to increased polarizability, the magnitude of these forces also significantly depends on the surface area available for interactions. Molecules with larger surface areas can have stronger dispersion forces due to more extensive contact between molecules.
5. Identify the false statement: 'Dispersion forces always have a greater magnitude in molecules with a greater molar mass.' This is not always true because the magnitude of dispersion forces also depends on the shape and surface area of the molecules, not just their molar mass.