Perchloric acid (formula HClO4) is a monobasic anhydrous acid. It contains chlorine (Cl) in the highest oxidation state, for this reason it is the strongest oxidizing agent. Explosive.
Properties of perchloric acid
1. It is a volatile liquid without color, smokes heavily in the air, monomer in vapors. Unstable and very reactionary. This acid is characterized by auto-dehydration:
3HClO4 = H3O + (cation) + ClO- (anion) + Cl2O7 (chlorine oxide)
2. This substance is readily soluble in organochlorine and fluorine solvents, such as CH2Cl2 (methylene chloride), CHCl3 (chloroform) and others. It mixes with other solvents, exhibits reducing properties, and if handled carelessly, it can lead to explosion or fire.
3. It mixes well with water (H2O) in any ratio. Forms several hydrates. Concentrated solutions of this acid have a slightly oily consistency. Aqueous solutions of this acid have good stability and low oxidative ability. The substance we are considering forms an azeotropic mixture with water, which boils at a temperature of 203 degrees and contains 72 percent HClO4.
4. Perchloric acid (formula HClO4) is one of the strongest acids. Because of this, in her environment, some acidic compounds behave like bases.
5. Under conditions of reduced pressure, with weak heating of a mixture of perchloric acid with phosphoric anhydride, an oily colorless liquid forms - chlorine anhydride:
2HClO4 (perchloric acid) + P4O10 (phosphoric anhydride) = Cl2O7 (chlorine anhydride) + H2P4O11
Production methods
1. Aqueous solutions of this substance can be obtained in two ways. The first is the electrochemical oxidation of chlorine or hydrochloric acid in concentrated hydrochloric acid, and the second is the exchange decomposition of sodium or potassium perchlorates with inorganic strong acids.
2. Anhydrous perchloric acid can also be obtained in two ways. The first consists in the interaction of potassium (K) or sodium (Na) perchlorates with sulfuric acid in a concentrated form, and the second - in the interaction of oleum with an aqueous solution of perchloric acid:
KClO4 (aqueous solution of perchloric acid) + H2SO4 (sulfuric acid) = KHSO4 (potassium hydrosulfate) + HClO4 (perchloric acid)
The use of perchloric acid
- concentrated solutions are widely used to obtain perchlorates (salts of this acid) and in analytical chemistry;
- perchloric acid is used in the decomposition of ores, as a catalyst and in the analysis of minerals;
- potassium perchlorate (formula: KClO4), a salt of this acid, is used to create explosives, and magnesium perchlorate (anhydrone, Mg (ClO4) 2) is used as a desiccant.
Safety at work
Anhydrous chloric acid cannot be stored and transported for a long time, since under standard conditions it decomposes quickly and can subsequently explode spontaneously.
Other inorganic chlorine acids:
1. Hydrochloric acid (formula: HCl) is a monobasic strong acid, a caustic liquid fuming in air. They are used in electroplating (pickling, pickling) and in hydrometallurgy, for cleaning metals by tinning and soldering, to produce manganese, zinc, iron and other metal chlorides. In the food industry, this substance is registered as a food additive E507.
2. Hypochlorous acid (formula: HClO) is a monobasic very weak acid. It can exist only in solutions. It is used for sanitary purposes, as well as for bleaching fabrics and cellulose.
3. Chloric acid (HClO2) - monobasic acid of medium strength. It is unstable in its free form; in a dilute aqueous solution it usually decomposes rapidly. The anhydride of this acid is still unknown.
4. Chloric acid (HClO3) - monobasic strong acid. Not obtained in free form, since it decomposes in concentrated solutions. In aqueous solutions, exists at a concentration below 30 percent. Quite stable at low temperatures.