Aerosol cans allow liquids to come out of their interior in the form of jets. But what factors contribute to this happening? The high pressure inside the container is what determines its use.
What causes the spray effect?
By pushing the pin down, we open the passage from the inside to the outside of the can. The contained propellant gas is liquefied due to the high pressure in the container, and at this point it is propelled out through the nozzle. The shape of the mouthpiece (very narrow orifice) causes the liquid to be sprayed in a fine spray.
The pressure of the gas inside the can is different from the outside, that is, the pressure inside the container is greater than the atmospheric pressure.
Applying to the concept "Law of gases":
A gas can go through three types of state variables: its volume, temperature and pressure. The equation below translates these variations:
This is known as the general gas equation, it addresses the three state variables (P, V, and T).
To understand this statement, look at a practical example: Why is it dangerous to leave empty spray cans exposed to heat?
If we lightly heat an empty can and press its valve, we will notice that there is still some amount of gas left. In the presence of fire (high temperatures), the remaining gas expands in such a way that it causes the can to explode.
As P, T, V are proportional quantities, the increase of one influences the increase of the other. Therefore, we have an increase in temperature and a consequent increase in volume and pressure.
This is why this object, when discarded, cannot be incinerated (burned).
By Líria Alves
Graduated in Chemistry
Brazil School Team
See more!
gas transformations
Experimental class – the behavior of gases
General chemistry - Chemistry - Brazil School
Source: Brazil School - https://brasilescola.uol.com.br/quimica/lei-dos-gases-aerossois.htm
