Is aluminum sulfate a precipitate?

Aluminum sulfate is a chemical substance that usually appears as white crystals or powder. It is generally used in industry, can be used to make paper and precipitants, and can also be used to make artificial gems. After being dissolved, aluminum sulfate can also turn into water, which is similar in color to drinking water, and has no special smell or color.

Is aluminum sulfate a precipitate?

Aluminum sulfate can be used to make precipitants, generally as industrial materials.

Physical and chemical properties

Physical properties

Appearance and properties: White crystals with sweet taste;

Solubility: soluble in water, insoluble in ethanol, etc.

Industrial products are grayish white flakes, granules or blocks. They are light green due to the low iron salt content, and the surface turns yellow due to the oxidation of low-valent iron salts. The crude product is a grayish white, fine-crystalline, porous substance.

It is highly soluble in water. Aluminum sulfate cannot be dissolved in pure sulfuric acid (they just coexist), but it can be dissolved in water together with sulfuric acid in a sulfuric acid solution. Therefore, the solubility of aluminum sulfate in sulfuric acid is the solubility of aluminum sulfate in water.

Aluminum sulfate chemical structure

770℃ decomposes into aluminum oxide and sulfur trioxide

There are anhydrous and octahydrate. The anhydrate is colorless orthorhombic crystals. Soluble in water, the aqueous solution is acidic, slightly soluble in ethanol. The solubility in water increases with increasing temperature. Octadecahydrate (Al2·(SO4)3·18H2O) is a colorless monoclinic crystal. Soluble in water, insoluble in ethanol. The aqueous solution is acidic due to hydrolysis.

Chemical properties

It is not easy to weather and lose crystal water, it is relatively stable, it will lose water when heated, and it will decompose into aluminum oxide and sulfur oxides at high temperature.

When heated to 770°C, it begins to decompose into aluminum oxide, sulfur trioxide, sulfur dioxide and water vapor. Soluble in water, acids and alkalis, insoluble in ethanol. The aqueous solution is acidic. After hydrolysis, aluminum hydroxide is generated. Prolonged boiling of aqueous solution can generate alkaline aluminum sulfate. Non-toxic, dust can irritate eyes.

The hydrolysis products are colloidal precipitates of alkali salt and aluminum hydroxide. It is easy to combine with potassium, sodium, and ammonium salts to form alum, such as potassium aluminum sulfate

kAl(SO4)2·12H2O.

When the hydrate is heated, it expands violently and becomes spongy. When heated to red heat, it decomposes into sulfur trioxide and aluminum oxide.