Although we do not see it or many times we are not aware of it, gases are always with us. Whether in the troposphere in which we breathe or in those stoves that made our food before the arrival of the glass-ceramic, the third state of matter (after solid and liquid) is a faithful companion . Characterized by the scarce union of its constituent particles, it lacks a defined shape and volume so it flows until it occupies the container that contains it. Some of the best known gases could be water vapor, carbon dioxide, methane or the air we breathe itself (which in turn is made up of various gases, including oxygen, hydrogen and nitrogen) ; but there are many other different gases that are interesting to know.
Starting with a simple case, we find helium. This noble gas is very popular because it is the favorite filling of balloons since, being a gas with a weight less than that of air, it makes them float. It is also this difference in weight that causes that, when a person breathes it in, their voice sounds much higher than usual. But what if the gas had a greater weight than the air? This is the case of sulfur hexafluoride , a peculiar odorless, colorless, non-toxic and non-flammable gas that weighs five times more than air.
Sulfur hexafluoride is often used as a temporary plug in retinal detachment operations and in the industrial world as a dielectric gas (it does not conduct current) to prevent discharges that can be dangerous. If sulfur hexafluoride is breathed in, its weight difference compared to air and helium makes the voice sound much lower. In addition, being heavier it can be kept in an open container so that, if we place a paper boat on it, it floats since the paper is lighter than sulfur hexafluoride .
We have already mentioned the atmosphere, the gaseous layer that is above us and that surrounds the Earth . Its weight also exerts interesting effects that, although invisible at first glance, can be demonstrated through a very simple experiment. In many films in which a submarine appears, we can see how the vehicle looks deformed or “crushed” under the external pressure exerted by water at shallow depths, but we can put this same effect to the test with a can, water and a source of hot. The first thing is to fill the can with water and heat it, then it is removed from the fire and as the temperature drops, the water vapor condenses, lowering the pressure on the inside walls of the container and causing the force that the atmosphere exerts on the can make it chafe . Like a submarine in the Mariana Trench.
