Each of us has come across the concepts of such a science as chemistry. Sometimes they are so similar that it is difficult to distinguish one from the other. But it is very important to understand all of them, because sometimes such a misunderstanding leads to very stupid situations, and sometimes to unforgivable mistakes. In this article we will tell you what hydrides are, which ones are dangerous and which are not, where they are used and how they are obtained. But let's start with a brief digression into history.
History
The history of hydrides begins with the discovery of hydrogen. This element was discovered by Henry Cavendish in the 18th century. Hydrogen, as you know, is part of water and is the basis of all other elements of the periodic table. Thanks to him, the existence of organic compounds and life on our planet is possible.
In addition, hydrogen is the basis for many inorganic compounds. Among them are acids and alkalis, as well as unique binary compounds of hydrogen with other elements - hydrides. The date of their first synthesis is not exactly known, but non-metal hydrides have been known to man since antiquity. The most common of these is water. Yes, water is oxygen hydride.
Also this class includes ammonia (the main component of ammonia), hydrogen sulfide, hydrogen chloride and similar compounds. Learn more about the properties of substances fromthis diverse and amazing class of compounds will be discussed in the next section.
Physical properties
Hydrides are mostly gases. However, if we take metal hydrides (they are unstable under normal conditions and react very quickly with water), then these can also be solid substances. Some of them (for example, hydrogen bromide) also exist in a liquid state.
It is simply impossible to give a general description of such a huge class of substances, because they are all different and, depending on the element that makes up the hydride, in addition to hydrogen, they have different physical characteristics and chemical properties. But they can be divided into classes, the compounds in which are somewhat similar. Below we will consider each class separately.
Ionic hydrides are compounds of hydrogen with alkali or alkaline earth metals. They are white substances, stable under normal conditions. When heated, these compounds decompose into their metal and hydrogen without melting. One exception is LiH, which melts without decomposition and, when heated strongly, turns into Li and H2.
Metal hydrides are compounds of transition metals. Very often they have a variable composition. They can be represented as a solid solution of hydrogen in a metal. They also have a metal crystal structure.
To covalent hydrides belongs just the type that is most common on Earth: compounds of hydrogen with non-metals. The wide area of distribution of these substances is due to theirhigh stability, since covalent bonds are the strongest of chemical bonds.
As an example, the formula for silicon hydride is SiH4. If we look at it in volume, we will see that hydrogen is very tightly attracted to the central silicon atom, and its electrons are shifted towards it. Silicon has a sufficiently high electronegativity, therefore, it is able to attract electrons to its nucleus more strongly, thereby reducing the bond length between it and the neighboring atom. And as you know, the shorter the bond, the stronger it is.
In the next section, we will discuss how hydrides differ from other compounds in terms of reactivity.
Chemical properties
In this section it is also worth dividing the hydrides into the same groups as in the past. And we will start with the properties of ionic hydrides. Their main difference from the other two types is that they actively interact with water with the formation of alkali and the release of hydrogen in the form of gas. The reaction of hydride - water is quite explosive, so the compounds are most often stored without moisture. This is done because water, even in the air, can initiate a dangerous transformation.
Let's show the equation of the above reaction using the example of a substance such as potassium hydride:
KH + H2O=KOH + H2
As we can see, everything is quite simple. Therefore, we will consider more interesting reactions characteristic of the other two types of substances we describe.
In principle, the rest of the transformations that we have not analyzed are characteristic of all types of substances. They aretend to react with metal oxides to form metal, either with water or with hydroxide (the latter is typical for alkali and alkaline earth metals).
Another interesting reaction is thermal decomposition. It occurs at high temperatures and passes before the formation of metal and hydrogen. We will not dwell on this reaction, since we have already analyzed it in the previous sections.
So, we have considered the properties of this type of binary compounds. Now it's time to talk about getting them.
Production of hydrides
Almost all covalent hydrides are natural compounds. They are quite stable, so they do not disintegrate under the influence of external forces. With ionic and metal hydrides, everything is a little more complicated. They do not exist in nature, so they have to be synthesized. This is done very simply: by the reaction of the interaction of hydrogen and the element whose hydride is to be obtained.
Application
Some hydrides have no specific application, but most are very important substances for industry. We will not go into details, because everyone has heard that, for example, ammonia is used in many areas and serves as an indispensable substance for the production of artificial amino acids and organic compounds. The use of many hydrides is limited by their chemical properties. Therefore, they are used exclusively in laboratory experiments.
Application is too broad a section for this class of substances, so we have limited ourselves to general facts. In the next part, we will tell you howmany of us, without proper knowledge, confuse harmless (or at least known) substances with each other.
Some delusions
For example, some people think that hydrogen hydride is something dangerous. If you can call this substance that, then no one does it. If you think about it, then hydrogen hydride is a combination of hydrogen with hydrogen, which means it is a H2 molecule. Of course, this gas is dangerous, but only when mixed with oxygen. In its pure form, it poses no danger.
There are many obscure names. They terrify the unaccustomed person. However, as practice shows, most of them are not dangerous and are used for domestic purposes.
Conclusion
The world of chemistry is huge, and we think that if not after this, then after several other articles, you will see for yourself. That is why it makes sense to immerse yourself in its study with your head. Mankind has discovered many new things, and even more remains unknown. And if it seems to you that there is nothing interesting in the field of hydrides, you are greatly mistaken.
