When liquid water transitions to a gas (a process known as evaporation or boiling, depending on the conditions), several changes occur at the molecular level:
-
Increased Energy: As the temperature increases, the kinetic energy of the water molecules also increases. This energy comes from heat added to the water.
-
Molecular Motion: In the liquid state, water molecules are relatively close together and can form hydrogen bonds with each other. As they gain energy, the molecules move faster and the distance between them increases.
-
Breakage of Hydrogen Bonds: The strong hydrogen bonds that hold water molecules together in the liquid state begin to break as the temperature rises. When these bonds break, the molecules can move freely and escape into the air as gas.
-
Phase Transition: At the boiling point (100°C or 212°F at standard atmospheric pressure), enough energy is provided to transition the majority of the water molecules into the gaseous state. The liquid and gas coexist during this transition.
-
Formation of Vapor: As more and more molecules gain sufficient energy and break away from the liquid, they disperse into the surrounding air as water vapor.
Overall, the transition from liquid to gas involves an increase in energy, increased molecular motion, the breaking of intermolecular bonds, and a change in physical state from liquid to vapor.