The adsorption

With the physicochemical phenomenon, which will now be discussed, probably everyone knows, although, perhaps, not everyone knows that it is called adsorption. Even if you did not pass adsorption in the classroom, you observed it repeatedly. As soon as you put an inkblot on paper or, worse, on clothes, then immediately get acquainted with this phenomenon. When the surface of one substance (paper, fabric, etc.) absorbs particles of another substance (ink, etc.), this is adsorption.

Even if you did not pass adsorption in the classroom, you observed it repeatedly

Very good adsorbent - coal. And not stone, but woody, and not just wood, but active (activated). Such coal is sold in pharmacies, usually in the form of tablets. From it we will begin experiments on adsorption.

Prepare a pale ink solution of any color and pour into a test tube, but not up to the top. Put in the test tube a tablet of active charcoal, close your finger and shake properly. The solution will lighten before our eyes. Change the solution to some other, but also painted - let it be diluted gouache or watercolor. The effect will be the same. And if you just take pieces of charcoal, they will absorb the dye much weaker.

In this there is nothing strange: the active coal differs from the usual in that it has a much larger surface. Its particles are literally permeated with pores (for this purpose, coal is treated in a special way and removed from the peg impurities). And if adsorption is an absorption by the surface, then clearly: the larger the surface, the better the absorption. Adsorbents are able to absorb substances not only from solutions. Take a half-liter glass jar and drop one drop of cologne or any other odorous substance to the bottom. Grab the jar with your hands and hold it so for half a minute to warm the odorant liquid a little. Now put a little bit of active coal in the bottle, close it tightly with a lid and leave it for a few minutes. Remove the cover. The smell disappeared. It was absorbed by the adsorbent, or rather, the molecules of the volatile matter that you placed in the jar were absorbed.

It is not necessary to take active coal for these experiments. There are many other substances that can serve as adsorbents: tuff, dry ground clay, chalk, blotting paper. You probably know how easily bread absorbs extraneous smells. It's not for nothing that wheat bread is not advised to be kept in one package with rye - their smells mix, and each loses its own special, only its inherent flavor.