Question

Rank the following chemicals from highest boiling point to

lowest and describe why. PCl3 , NCl3, PH3, and NH3.

Answer 1

The order from highest to lowest boiling point is: NH3 > NCl3 > PCl3 > PH3. Considering the intermolecular forces, NH3 has the highest boiling point due to hydrogen bonding, followed by NCl3 and PCl3 which are influenced by dipole-dipole interactions and molar mass. PH3 has the lowest boiling point because it only has weak London dispersion forces.

Step-by-step explanation:

To rank the boiling points of the compounds PCl3, NCl3, PH3, and NH3 from highest to lowest, we need to consider the types of intermolecular forces present in each substance.

• NH3 has the ability to form hydrogen bonds due to the presence of a nitrogen atom bonded to hydrogen. This results in a higher boiling point.
• Both PCl3 and NCl3 are polar molecules and will experience dipole-dipole interactions. However, NCl3 has a higher molar mass and is expected to have also stronger van der Waals forces, leading to a higher boiling point compared to PCl3.
• PH3 has the lowest molar mass and is nonpolar, thus it only experiences weak London dispersion forces and has the lowest boiling point.

Therefore, the order from highest to lowest boiling point is: NH3 > NCl3 > PCl3 > PH3.