Rank the compounds NH3, CH4, PH3 in order of increasing boiling point. Explain your answer.

Question from a reader: Rank the compounds NH3, CH4,PH3 in order of increasing boiling point. Explain your answer.

• NH3 is highest because the N-H bonds give it Hydrogen Bonding Intermolecular Forces.
• PH3 is next highest because it has dipole dipole forces, which are weaker than “hydrogen bonding"
  
• CH4 has neither of those. It only has London Dispersion forces which are weak. It has the lowest boiling point of the three.