Water (H₂O):
* Strong Hydrogen Bonding: Water molecules have a highly polar structure, with oxygen being more electronegative than hydrogen. This creates strong hydrogen bonds between water molecules. These bonds are the strongest type of intermolecular force.
* High Boiling Point: Because of the strong hydrogen bonds, water has a relatively high boiling point (100°C). A lot of energy is needed to break these bonds and allow water to transition from liquid to gas.
* Liquid at Room Temperature: The strong hydrogen bonding in water makes it a liquid at room temperature (25°C). The energy present at room temperature is not sufficient to overcome the strong hydrogen bonding, keeping the molecules close together in a liquid state.
Ammonia (NH₃):
* Weaker Hydrogen Bonding: While ammonia also forms hydrogen bonds, they are weaker than those in water. This is because nitrogen is less electronegative than oxygen, resulting in weaker dipole-dipole interactions.
* Lower Boiling Point: The weaker hydrogen bonds in ammonia lead to a much lower boiling point (-33.3°C). Less energy is required to break these bonds and allow ammonia to transition from liquid to gas.
* Gas at Room Temperature: The relatively weak hydrogen bonding in ammonia means that at room temperature (25°C), the molecules have enough energy to overcome the intermolecular forces and exist as a gas.
In summary: The difference in boiling points and physical state between water and ammonia at room temperature is primarily due to the strength of their intermolecular forces, particularly hydrogen bonding. Water's strong hydrogen bonding holds its molecules together as a liquid, while ammonia's weaker hydrogen bonding allows it to exist as a gas.
