What is an acid or salt, most are well aware. It is difficult to find a person who did not hold a bottle of vinegar in his hands or did not use a food product in his life, without which almost any food seems fresh and tasteless. But what is alkali? Is it the same as the foundation, or not? How is it different from acid? Such questions can perplex anyone, and therefore let us refresh the knowledge that was once obtained at school.
Alkali - what is it?
To begin with, metal compounds with water are commonly called hydroxides in chemistry. A substance of this type, formed by ammonium, an alkaline or alkaline earth metal, is called an alkali. In turn, the base is an electrolyte, in which, in addition to hydroxide ions (OH - ), there are no other anions. Thus, we can say that alkali is any soluble base. Only metals of subgroups Ia and IIa (those that come after calcium) can form such a hydroxide. An example of such compounds is sodium alkali (NaOH formula), caustic barium (Ba (OH) 2 ), potassium hydroxide (KOH), cesium hydroxide (CsOH), etc. By themselves, they are solid white substances, which are characterized by high hygroscopicity.
Alkali Properties
Dissolution of such compounds in water is accompanied by significant heat release. In group Ia, the strongest alkali is cesium hydroxide, and in group IIa, radium hydroxide. An example of a weak compound of this type is ammonia and hydrated lime. Caustic alkali can dissolve in ethanol and methanol. In the solid state, all these substances absorb water and carbon dioxide from the air and slowly turn into carbonates. The most important property of alkali is that salt is formed as a result of its reaction with acid - this feature is very often used in industry. An electric current can pass through these compounds, and therefore they are often used as electrolytes. Alkali is obtained by electrolysis of chlorides or through the interaction of alkali metal oxides with water. In industry, the first method is usually used, and the second is mainly used to produce slaked lime. Fat is dissolved in an alkaline environment, and this property is widely used in the manufacture of soaps. A number of bases can destroy plant and animal tissues, irritate the skin and destroy clothes. Alkalis can react with certain metals (for example, aluminum) and are able to protect steel from corrosion. They are resistant to heat - sodium hydroxide can be melted and brought to a boil, but it will not decompose.
This alkali is very different from insoluble bases, some of which (for example, silver hydroxide) decomposes even at room temperature. Like acids, these substances require extreme caution and place high demands on safety recommendations. To protect the eyes when working with alkali, glasses are usually worn. They can only be stored in special vessels - drinking containers are completely unsuitable for this.