How to mix two liquid substances? For example, some acid and water? This task from a series "twice two – four" would seem. What can be simpler: to merge two liquids together, in some suitable capacity, and put everything! Or to pour in one liquid in the capacity where there is already another. Alas, it is that simplicity which, on an apt national expression, is worse than theft. As business can end extremely sadly!
Instruction
1. There are two containers, one of them contains the concentrated sulfuric acid, in another – water. How it is correct to mix them? To pour acid into water or, on the contrary, water in acid? At the price of the incorrect decision in the theory there can be a low mark, and in practice - at best, a severe burn.
2. Why? But because the concentrated sulfuric acid, first, is much more dense than water, and secondly, is extremely hygroscopic. In other words, it actively absorbs water. Thirdly, this absorption is followed by allocation of a large amount of heat.
3. If in the container with the concentrated sulfuric acid begin to flow water, the first portions of water "will spread" on the surface of acid (as water much less dense), and acid will begin to absorb greedy it, generating heat. And there will be a lot of this heat that water literally "will boil" and splashes will depart extensively. Naturally, without having passed the unlucky experimenter. To burn also "pure" boiled water not really pleasantly and if to consider that in water splashes for certain there will be still acid. The prospect becomes absolutely gloomy!
4. For this reason many generations of teachers-chemists forced the pupils to jag the rule literally: "At first water, then – acid! Otherwise there will be a big trouble!" The concentrated sulfuric acid should be added to water, small portions, when hashing. Here then the above unpleasant situation will not occur.
5. Reasonable question: with sulfuric acid clear and how to be with other acids? How it is correct to mix them with water? In what order? It is necessary to know acid density. If it is more dense than water, for example, concentrated nitric, its just as sulfuric, it is necessary to flow in water, meeting the above-stated conditions (gradually, when hashing). Well, and if acid density very slightly differs from water density, as in a case with acetic acid, all the same here.