Answer to Question #287752 in General Chemistry for mae

Question

Arrange the following according to decreasing intermolecular force of attraction. Explain your answer.

1. Water
2. barium chloride
3. phophorus trichloride
4. bromine

Answer 1

C. sodium chloride (NaCl) Melting point 800,8 оС

B. water (H2O) Boiling point 100 оС

D. iodine-chloride (ICl) Boiling point 97,4 оС

A. carbon tеtrachloride (CCl4) Boiling point 76,8 оС

Any conclusions about intermolecular forces may be made after the comparing of boiling points, because it explains how much must be added to break the intermolecular bonds. Also must be remembered that intermolecular forces have static nature.

Sodium chloride is solid at room temperature. It has ionic structure and ions as oppositely charged particles attract to each other very much. That’s why it melts at so high temperature.

Other compounds are liquids at room temperatures, that’s why their intermolecular forces of attraction are weaker. The molecules of water are very polar. There are a lot of hydrogen bonds that associate water molecules increasing boiling point in this way.

The molecule of ICl is polarized as well. It exists as I+ ‒ Cl-. That’s why there’re some kind of static interactions between oppositely polarized endings of two different molecules. The distinction between electronegativities of I and Cl is less significant than in case of H and O. That’s why intermolecular force of attraction in ICl is weaker than in water.

Finally the molecule of CCl4 is absolutely non-polar. Any static interactions must be included. The molecules are bond by another types of forces and their interactions may be described by another mechanisms, but that forces are weaker than static cooperations, that’s why CCl4 is at the last position.