What is an acid or a s alt, most are well aware. It is difficult to find a person who has not held a bottle of vinegar in his hands or has not used a food product in his life, without which almost any food seems bland and tasteless. But what is alkali? Is it the same as base or not? How is it different from acid? Such questions can puzzle anyone, and therefore let us refresh the knowledge that was once obtained at school.
Alkaline - what is it?
Let's start with the fact that compounds of metals with water in chemistry are usually called hydroxides. A substance of this type, formed by ammonium, an alkali or alkaline earth metal, is called 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 an alkali is any soluble base. Formsuch a hydroxide can only be metals of subgroups Ia and IIa (those that come after calcium). An example of such compounds is sodium alkali (formula NaOH), caustic baryate (Ba(OH)2), potassium hydroxide (KOH), cesium hydroxide (CsOH), etc. They are solid white substances, which are characterized by high hygroscopicity.
Properties of alkalis
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 slaked lime. Caustic alkalis are able to 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 as a result of its reaction with an acid, a s alt is formed - this feature is very often used in industry. Electrical current can flow through these compounds and are therefore often used as electrolytes. Alkalis are 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 used for the most part for the production of slaked lime. Fat dissolves in an alkaline environment, and this property is widely used in the manufacture of soap. A number of bases can destroy plant and animal tissues, irritate the skin and destroy clothing. Alkalis can react with some metals (for example,with 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.
In this, alkalis are very different from insoluble bases, some of which (for example, silver hydroxide) decompose already at room temperature. Just like acids, these substances require great care and pose high requirements for adherence to safety recommendations. Goggles are usually worn to protect the eyes when working with lye. It is allowed to store them only in special vessels - drinking containers are absolutely not suitable for this.
