A chemical base is all that substance that when dissolved releases hydroxyl ions (OH – ). Chemical bases are also known as alkalis, because as the hydroxyl groups dissociate and release, the pH of the solutions increases, that is, the solution becomes alkaline. This is contrary to what happens when acid dissolves because in that case the pH decreases and the solution becomes acidic.
The bases have a characteristic bitter taste. After dissolution, the resulting solutions conduct the electric current (due to the presence of ions) and are usually caustic and irritating to the skin and other human and animal tissues. Bases neutralize acids, often forming salts. Alkaline solutions tend to be perceived as slippery or soapy; This happens because they immediately produce the saponification of the fats present on the surface of the skin.
The solubility of the hydroxides depends on the metal: those of group (I) are the most soluble in water, on the other hand, the hydroxides of the elements with a degree of oxidation (II) are less soluble and those of degree of oxidation (III) or (IV) is almost insoluble. Amines and nucleic acid bases are the most widespread bases among organic ones.
Uses of bases
Sodium hydroxide is widely used in industry: it is the so-called caustic soda. Animal or vegetable fats are used to make the soap, which is boiled with sodium hydroxide, thus forming sodium stearate.
Sodium hydroxide is also used in the manufacture of oven cleaners, in the manufacture of paper pulp, and in some household cleaners. Another widely used base is calcium hydroxide, which is slaked lime used in construction.
Examples of chemical bases
|sodium hydroxide (caustic soda)
|calcium hydroxide (lime)
|magnesium hydroxide (milk of magnesia)
|aluminum hydroxide (antacid)