Why does the pressure of a gas increase when it is compressed? The answer to this question concerns the movement of gas molecules in a closed bottle, see:
Red particles: molecules in the gaseous state.
A careful observation of the illustration allows us to see that, in a smaller space, the molecules are more concentrated. When compressing a gas, it starts to exert certain pressure on the walls of the container. The rapid and continuous movement of molecules colliding with the walls is what makes the phenomenon possible.
Therefore, to increase the pressure of a gas it is not necessary to increase its temperature, just decrease its volume (compress the gas).
On the other hand, for an increase in Average Kinetic Energy (Ecin) it is necessary to promote a change in the temperature of the gas.
When we heat the gas inside the flask, the molecules present start to move with greater speed, which causes an increase in the average kinetic energy. We then say that Ecin is directly proportional to temperature, as shown in the equation:
ANDcin = KT
The gas that obeys this equation is considered a perfect gas (or ideal gas).
By Líria Alves
Graduated in Chemistry
Brazil School Team
See more!
Gases – learn more about this class of compounds.
General chemistry - Chemistry - Brazil School
Source: Brazil School - https://brasilescola.uol.com.br/quimica/teoria-cinetica-dos-gases.htm