Boiling point

[Kaitlynn Tran 3F]

So I know that the relative strengths for bonds are ionic > hydrogen > dipole-dipole > london dispersion, and as the bonds get stronger, the boiling point gets higher due to more energy required to break the bond. However, factors such as molecular size and surface area are factors that increase boiling point as well.

When comparing two molecules such as NH₃ and PH₃, which would have a higher boiling point? NH₃ has hydrogen bonding, but PH₃ has a larger molecular size, so I don't know how to rank them.

[Midori Hupfeld 3D]

First, remember to say the strengths of the intermolecular forces between compounds, because it is not the actual intramolecular bonds. Also, NH3 has the greater boiling point, because it actually has hydrogen bonding (remember that you can form hydrogen bonds only on Hydrogens that are bonded to N, O, or F).

[Kaitlynn Tran 3F]

First, remember to say the strengths of the intermolecular forces between compounds, because it is not the actual intramolecular bonds. Also, NH3 has the greater boiling point, because it actually has hydrogen bonding (remember that you can form hydrogen bonds only on Hydrogens that are bonded to N, O, or F).

So hydrogen bonding would result in a higher boiling point than having a larger molecular size would?

[Charysa Santos 4G]

Yes, hydrogen bonding would result in a higher boiling point because compared to the PH3, Nitrogen has far greater electronegativity, which means that it is able to form much stronger (hydrogen) bonds which require more energy to break (as in boiling).

[Nan_Guan_3J]

NH3 can be considered as a special case because it has hydrogen bond which is relatively strong. NH3 and PH3 have similar molar mass.