Answer to Question #299762 in General Chemistry for Ellea

Question

Rank the following compounds from weakest to strongest intermolecular forces. Justify your answer.

1. a. H₂S b. I₂ c. N₂ d. H₂O

2. a. H₂Se b. H₂S c. H₂Po d. H₂Te

Answer 1

1.a.

N₂ < I₂ < H₂S < H₂O

N₂ and I₂ are nonpolar, so they only have dispersion forces;

I₂ has stronger forces because it is larger

H₂S has dipole-dipole, so it is stronger than I₂

H₂O has hydrogen bonding, so it is stronger than H₂S 

2.(a)

H₂S < H₂Se < H₂Te < H₂Po

These compounds are all the same shape. Although H₂S is slightly more polar than the others, it is not very polar so it has very weak dipole-dipole forces. Therefore, the difference in dispersion forces are more important for these compounds. H₂Po is the largest and, therefore, has the strongest dispersion forces.