The appearance of the substance is aluminum hydroxide as follows. As a rule, this substance is white, gelatinous, although there are variants of the presence in a crystalline or amorphous state. For example, when dried, it crystallizes into white crystals, which do not dissolve in either acids or alkalis.
Aluminum hydroxide can also be represented by white crystalline powder. The presence of pink and gray shades is acceptable.
The chemical formula of the compound is Al (OH) 3. The aluminum oxide and water compounds form aluminum hydroxide , the chemical properties of which are also determined in many respects by the elements that make up its composition. This compound is obtained by carrying out the reaction of the interaction of an aluminum salt and dilute alkali, while avoiding their excess. The aluminum hydroxide precipitate obtained during this reaction can then react with acids.
Aluminum hydroxide interacts with an aqueous solution of rubidium hydroxide, an alloy of this substance, cesium hydroxide, cesium carbonate. In all cases, water is released.
Aluminum hydroxide has a molecular mass of 78.00, practically insoluble in water. The density of the substance is 3.97 grams / cm3. Being an amphoteric substance, aluminum hydroxide interacts with acids, and, as a result of reactions, medium salts are obtained and water is released. When reacting with alkalis, complex salts appear - hydroxoaluminates, for example, K [Al (OH) 4 (H2O) 2]. Metaaluminates are formed when aluminum hydroxide is fused with anhydrous alkalis.
Like all amphoteric substances, aluminum hydroxide simultaneously shows acidic and basic properties when interacting with strong acids, as well as with alkalis. In these reactions, when the hydroxide is dissolved in acids, the ions of the hydroxide itself are cleaved, and when interacting with alkali, the hydrogen ion is cleaved. To see this, for example, you can conduct a reaction in which aluminum hydroxide, sodium hydroxide are involved . To carry it out, it is necessary to fill in a test tube a little aluminum sawdust and pour a small amount of sodium hydroxide, not more than 3 milliliters. The tube should be tightly closed with a stopper, and slow heating should begin. After that, having fixed the test tube on a tripod, it is necessary to collect the separated hydrogen into another test tube, after having put it on the capillary device. After about a minute, the tube should be removed from the capillary and brought to a flame. If pure hydrogen is collected in a test tube, combustion will occur calmly, in the same case, if air gets into it, cotton will occur.
Get aluminum hydroxide in laboratories in several ways:
- by the reaction of interaction of aluminum salts and alkaline solutions;
- the method of decomposition of aluminum nitride under the influence of water;
- by passing carbon through a special hydrocomplex containing Al (OH) 4;
- the effect of ammonia hydrate on aluminum salts.
Industrial production is associated with the processing of bauxite. Technologies are also used to influence aluminate solutions with carbonates.
Aluminum hydroxide is used in the manufacture of mineral fertilizers, cryolite, various medical and pharmacological preparations. In chemical production, the substance is used to produce aluminum fluoride and sulfur. An indispensable combination in the manufacture of paper, plastics, paints and much more.
Medical use is due to the positive effect of drugs containing this element in the treatment of gastric disorders, increased acidity of the body, and peptic ulcers.
When handling the substance, be careful not to inhale its vapors, as they cause severe lung damage. Being a weak laxative, it is dangerous in large doses. Corrosion causes aluminum.
The substance itself is quite safe, since it does not react with oxidizing agents.