Hydrides are ... The use of hydrides

Each of us has come across terms of science such as chemistry. Sometimes they are so similar that it is difficult to distinguish one from another. But it is very important to understand all of them because sometimes this misunderstanding leads to very foolish situations, and sometimes to unpardonable mistakes. In this article we will describe what hydrides are, which of them are dangerous, and which are not, where they are applied and how they are obtained. But we will begin with a short digression into history.

History

The hydrides begin their history with the discovery of hydrogen. This element was discovered in the 18th century by Henry Cavendish. Hydrogen, as is known, is a part of water and is the basis of all the 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, acids and alkalis, as well as unique binary compounds of hydrogen with other elements - hydrides. The date of their first synthesis is not known exactly, but hydrides of non-metals 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 the like. More details about the properties of substances from this diverse and surprising 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 it can be solid substances. Some of them (for example, hydrogen bromide) exist also in the 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 in the hydride, besides hydrogen, have different physical characteristics and chemical properties. But they can be divided into classes, the connections in which something similar. Below, we will consider each class separately.

Ionic hydrides are compounds of hydrogen with alkaline or alkaline-earth metals. They are substances of white color, stable under normal conditions. When heated, these compounds decompose into the metal and hydrogen entering into their composition without melting. One exception is LiH, which melts without decomposition and under strong heating turns into Li and H ₂ .

Metal hydrides are compounds of transition metals. Very often have a variable composition. They can be represented as a solid solution of hydrogen in a metal. Also have the crystal structure of the metal.

Covalent hydrides belong exactly to the species that most often occurs on Earth: hydrogen compounds with nonmetals. The wide range of these substances is due to their high stability, since covalent bonds are the strongest of chemical substances.

As an example, the formula of silicon hydride: SiH ₄ . If we look at it in volume, we see that hydrogen is very tightly attracted to the central silicon atom, and its electrons are shifted to it. Silicon has a sufficiently large electronegativity, so it is able to attract electrons to its core, thus shortening the length of the connection between it and the neighboring atom. And as you know, the shorter the connection, the stronger it is.

In the next section, we discuss how hydrides differ from other compounds in terms of chemical activity.

Chemical properties

In this section, it is also worthwhile to divide the hydrides into the same groups as in the past. And we will start with the properties of ion hydrides. Their main difference from the other two species is that they actively interact with water to form alkali and release of hydrogen in the form of gas. The reaction hydride-water is quite explosive, so the connections are most often stored without access to moisture. This is done because water, even contained in the air, can initiate a dangerous transformation.

We shall show the equation of the above-described reaction using an example of a substance such as potassium hydride:

KH + H ₂ O = KOH + H ₂

As we can see, everything is quite simple. Therefore, consider the more interesting reactions characteristic of the other two species of the substances described by us.

In principle, the remaining transformations, which we have not disassembled, are characteristic of all types of substances. They tend to interact with metal oxides, forming a metal, either with water or with a hydroxide (the latter is characteristic of alkaline and alkaline-earth metals).

Another interesting reaction is thermal decomposition. It occurs at high temperatures and passes to the formation of metal and hydrogen. We will not dwell on this reaction, since we have already discussed it in the previous sections.

So, we have examined the properties of this kind of binary compounds. Now it's worth talking about getting them.

Preparation of hydrides

Almost all covalent hydrides are natural compounds. They are sufficiently stable, therefore they do not disintegrate under the action of external forces. With ionic and metallic 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 reaction of the interaction of hydrogen and the element, the hydride of which is required to be obtained.

Application

Some hydrides do not have a specific application, but most are very important substances for the industry. We will not go into details, because everyone has heard that, for example, ammonia is used in many spheres and serves as an indispensable substance for obtaining artificial amino acids and organic compounds. The use of many hydrides is limited by the peculiarities of their chemical properties. Therefore, they are used exclusively in laboratory experiments.

The application is too extensive a section for this class of substances, so we confined ourselves to general facts. In the next part, we will tell you how many of us, without proper knowledge, confuse innocuous (or at least known) substances among themselves.

Some misconceptions

For example, some believe that hydrogen hydride is something dangerous. If you can call this substance so, then no one does. If you think about it, hydrogen hydride is a hydrogen compound with hydrogen, which means a molecule H ₂ . Of course, this gas is dangerous, but only in a mixture with oxygen. In its pure form, it does not pose a danger.

There are many strange names. Unaccustomed to a man they are horrified. 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's why it makes sense to immerse yourself in learning it with your head. Mankind has discovered many new things, and still remains unknown. And if it seems to you that in the field of hydrides there is nothing interesting, you are greatly mistaken.