Question

Place the following compounds in order of increasing strength of intermolecular forces.

CO₂ F₂ NH₂CH₃

A) NH₂CH₃ < CO₂ < F₂
B) F₂ < NH₂CH₃ < CO₂
C) NH₂CH₃ < F₂ < CO₂
D) F₂ < CO₂ < NH₂CH₃

Answer 1

The compounds should be arranged in the following order of increasing strength of intermolecular forces: NH₂CH₃ < CO₂ < F₂. London dispersion forces (LDF) are the only intermolecular forces present in all three compounds.

Step-by-step explanation:

The compounds should be arranged in the following order of increasing strength of intermolecular forces: NH₂CH₃ < CO₂ < F₂.

The strength of intermolecular forces can be determined by considering the types of forces present. In this case, London dispersion forces (LDF) are the only intermolecular forces present in all three compounds. LDF are the weakest intermolecular forces and are caused by temporary fluctuations in electron distribution, resulting in temporary dipoles.

Among the three compounds, F₂ has the largest molecular size and therefore the greatest number of electrons, resulting in stronger LDF. CO₂ is smaller than F₂ but larger than NH₂CH₃, so its LDF is stronger than NH₂CH₃ but weaker than F₂. Therefore, the correct order is NH₂CH₃ < CO₂ < F₂.