Account for the following observation:
1)Ammonia is exceptionally soluble in water.
2)Hydrogen fluoride ,HF, has a higher boiling temperature than methane, CH4.
3)The boiling temperature of ammonia (NH3)is -33˚C but that of phosphine (PH3) is -88˚C
To account for the observations listed above, we need to consider the molecular properties and interactions of these substances.
1) Ammonia is exceptionally soluble in water:
The exceptional solubility of ammonia (NH3) in water can be attributed to hydrogen bonding. Ammonia is a polar molecule, meaning it has a partial positive charge on its hydrogen atoms and a partial negative charge on its nitrogen atom. Water molecules, also polar, can form hydrogen bonds with the hydrogen atoms of ammonia. This allows ammonia to dissolve readily in water, forming ammonium hydroxide (NH4OH).
2) Hydrogen fluoride (HF) has a higher boiling temperature than methane (CH4):
The difference in boiling temperature between hydrogen fluoride (HF) and methane (CH4) is due to differences in intermolecular forces. Both molecules are nonpolar, but hydrogen fluoride can exhibit stronger intermolecular hydrogen bonding compared to methane. The hydrogen bonding between HF molecules leads to stronger attractive forces, requiring more energy to overcome and thus resulting in a higher boiling point.
3) The boiling temperature of ammonia (NH3) is -33˚C, but that of phosphine (PH3) is -88˚C:
The difference in boiling temperature between ammonia (NH3) and phosphine (PH3) can be explained by the differences in molecular mass and molecular polarity. Ammonia has a lower boiling point because it is lighter and has a smaller molecular size compared to phosphine. Additionally, ammonia is a polar molecule, allowing it to form hydrogen bonding, which contributes to stronger molecular attractions and higher boiling temperature compared to nonpolar phosphine.
In summary, the exceptional solubility of ammonia in water can be attributed to hydrogen bonding, whereas the difference in boiling temperatures between hydrogen fluoride and methane, as well as between ammonia and phosphine, can be explained by differences in intermolecular forces, molecular size, and polarity.