boiling point of ammonia is lower than benzene. why?
The boiling point of a substance is determined by the strength of the attractive forces between its molecules. Molecules with stronger intermolecular forces tend to have higher boiling points.
In the case of ammonia (NH3) and benzene (C6H6), ammonia has a lower boiling point because it has weaker intermolecular forces compared to benzene.
Ammonia molecules are attracted to each other by a type of intermolecular force called hydrogen bonding. Hydrogen bonding occurs when the hydrogen atom in one molecule is attracted to the electronegative atom (in this case, nitrogen) in another molecule. Although hydrogen bonding is stronger than other intermolecular forces like dipole-dipole interactions or London dispersion forces, it is weaker than benzene's intermolecular forces.
On the other hand, benzene molecules engage in a type of intermolecular force known as π (pi) interactions or π stacking. These interactions occur between the π electrons in benzene rings, creating a strong attractive force. As a result, benzene has stronger intermolecular forces than ammonia, leading to a higher boiling point.
To determine the boiling points of substances, one way is to consider their intermolecular forces and compare them. Additionally, experimental data or reference tables can be used to find the exact boiling points of specific substances.