Is vaporization endothermic or exothermic?
The correct answer and explanation is:
Vaporization is an endothermic process.
When a substance undergoes vaporization, it absorbs heat energy from the surroundings. This energy is required to break the intermolecular forces between the particles of the substance, which allows them to transition from a liquid phase to a gaseous phase. The process of vaporization occurs when the liquid molecules gain enough energy to overcome the attractive forces of the liquid state and escape into the air as vapor.
There are two types of vaporization: evaporation and boiling. Evaporation happens at the surface of a liquid and can occur at any temperature, provided the liquid molecules at the surface have enough energy to escape into the gas phase. Boiling, on the other hand, occurs when a liquid reaches its boiling point, and the vaporization takes place throughout the entire liquid mass.
The key factor here is that during vaporization, the molecules of the liquid absorb energy from the environment in the form of heat. This energy is used to increase the kinetic energy of the molecules, allowing them to break free from the intermolecular forces holding them in the liquid state. Since this energy is absorbed and not released, the process is considered endothermic.
In practical terms, this is why a puddle of water feels cooler as it evaporates. The liquid water absorbs heat from its surroundings to vaporize, leading to a decrease in the temperature of the water and its environment.
Thus, vaporization is an endothermic process because it requires energy input to overcome the forces binding molecules in the liquid phase, allowing them to escape into the gas phase.