Boiling Point Order of NH3, PH3, AsH3, SbH3, BiH3

Understanding the Molecular Structure and Intermolecular Forces:

- The boiling point of a substance is determined by the strength of intermolecular forces present in the molecule.
- The stronger the intermolecular forces, the higher the boiling point of the substance.
- Intermolecular forces include hydrogen bonding, dipole-dipole interactions, and van der Waals forces.

Analyzing the Molecules NH3, PH3, AsH3, SbH3, BiH3:

- NH3 (Ammonia): NH3 molecules form hydrogen bonds due to the presence of a lone pair on nitrogen, leading to strong intermolecular forces.
- PH3 (Phosphine): PH3 molecules can exhibit weak dipole-dipole interactions but do not form hydrogen bonds.
- AsH3 (Arsine): AsH3 molecules have weaker intermolecular forces compared to NH3 due to larger size and less electronegative atoms.
- SbH3 (Stibine): SbH3 molecules have weaker intermolecular forces compared to AsH3 due to increased size and weaker dipole interactions.
- BiH3 (Bismuthine): BiH3 molecules have the weakest intermolecular forces among the group due to the larger size and less polar nature.

Arranging the Molecules in Boiling Point Order:

- NH3 has the highest boiling point due to strong hydrogen bonding.
- PH3 has a lower boiling point than NH3 due to weaker intermolecular forces.
- AsH3 has a lower boiling point than PH3 due to weaker dipole-dipole interactions.
- SbH3 has a lower boiling point than AsH3 due to larger size and weaker forces.
- BiH3 has the lowest boiling point among the group due to the weakest intermolecular forces.

Therefore, the boiling point order is NH3 > PH3 > AsH3 > SbH3 > BiH3 based on the strength of intermolecular forces in the molecules.