Vaporization is the name given to the physical transformation of liquid state to the gaseous state. In this transformation there are only changes in the physical character of the matter, that is, after its occurrence, the matter remains with the same constitution (composition).
The physical parameters that are changed during vaporization are:
Molecular breakdown: Molecules become free as a result of disruption of intermolecular interactions or intermolecular forces (such as hydrogen bonds, dipole-dipole and induced dipole);
Intense increase in kinetic energy molecules (molecules present a greater amount of heat than in liquid and solid states);
Increased Molecular Mobility (molecules become more agitated);
The article starts to present a totally dependent form the place where it is stored;
The article starts to present a variable volume.
For vaporization to occur, it is essential that matter in the liquid state receives energy (endothermic process) sufficient for the disruption of intermolecular forces. The temperature required for all the liquid to be transformed into a gas is called the boiling point (PE). Water, for example, has a boiling point equal to 100
OÇ.It is noteworthy that it is not necessary for the liquid to reach its boiling point for it to undergo vaporization, as the intermolecular forces of molecules on the surface of the liquid are more fragile and can be broken at higher temperatures low. An example of this is drying clothes on the clothesline, as the water present in the clothes vaporizes at temperatures much lower than 100OÇ.
Thus, we can highlight that there are fundamental factors for vaporization to happen. Are they:
Atmospheric pressure
Boiling point
Intensity of heat supplied to the liquid
The) Atmospheric pressure
It is the force that the atmosphere (air) exerts on the liquid's surface. The higher the atmospheric pressure, the more difficult it is for vaporization to occur. Thus, for this process to take place, it is necessary that the amount of heat supplied to the liquid is greater.
b) boiling point
It is the temperature at which there is complete disaggregation of all the molecules that formed the liquid, which results in the transformation into a gas. This property is completely dependent on the type of force existing between the molecules.
The order of strength of intermolecular interactions is shown below:
induced dipole < permanent dipole < hydrogen bonding
Thus, the greater the strength of the force existing between the molecules, the higher the boiling point.
c) Intensity of heat supplied to the liquid
The amount of heat supplied to the liquid causes its molecules to become more agitated and promotes the disruption of the intermolecular forces that keep them together. The greater the amount of heat absorbed by the liquid, the faster it will vaporize.
Taking into account the heat provided, we can call vaporization by three other distinct names:
-
Evaporation: Vaporization that happens slowly, since the article is receiving a small amount of heat. A practical example of evaporation is putting wet clothes on the clothesline.
The water present in clothes on the clothesline evaporates -
boiling: vaporization what happens quickly, given that the article is receiving a high amount of heat. A practical example of boiling is putting water in the pot and heating it over a stove flame.
Water being heated and boiling Heating: Vaporization that happens extremely fast (instant), as the matter is receiving a very high amount of heat. A practical example of boiling is when an iron is too hot and touches a wet garment, or when a drop of liquid water comes into contact with a very hot oil.
Iron promoting water heating on clothes
By Me. Diogo Lopes Dias
Source: Brazil School - https://brasilescola.uol.com.br/o-que-e/quimica/o-que-e-vaporizacao.htm