Potassium aluminum sulfate dodecahydrate

Many families have alum, which is also known as potassium aluminum sulfate dodecahydrate. It has a good disinfecting effect when placed in the toilet. It is chemically classified as a mixed complex salt of potassium sulfate and aluminum sulfate. It is a white crystal. Sometimes potassium aluminum sulfate dodecahydrate will also appear translucent. It will produce precipitation when dissolved in water. The following is a detailed introduction to the specific relevant information of potassium aluminum sulfate dodecahydrate.

Alum (pronounced: Bái Fán) (English: ALUMEN), also known as potassium aluminum alum, aluminum alum, potassium alum, alum, and raw alum, is a complex salt of potassium sulfate and aluminum sulfate containing water of crystallization, with the chemical formula KAl(SO4)2‧12H2O. The chemical name is potassium aluminum sulfate dodecahydrate. It is a crystal formed by processing and refining the mineral alunite. Colorless cubic crystals, often octahedral in appearance, or forming aggregates with cubes and rhombic dodecahedrons. Sometimes attached to the container wall with 111 faces and shaped like a hexagonal plate. It belongs to the α-type alum complex salt and has a glassy luster. It has antibacterial and astringent effects, can be used as a traditional Chinese medicine, and belongs to the lung, spleen, liver, and large intestine meridians. Alum can also be used to prepare aluminum salts, baking powder, paint, tanning agents, clarifiers, mordants, papermaking, waterproofing agents, etc. It can also be used as a food additive. Soak your feet in a ratio of 10% alum to 90% warm water twice a week. The powder can be ground into powder and soaked in water to treat athlete's foot.

Properties: Alum belongs to the trigonal crystal system. The crystals are small rhombohedral or plate-like, usually in the form of dense blocks, fine particles, or soil. The color is colorless or white, often with light yellow and light red. The streak is white.

The luster is glassy, sometimes with a slight pearly luster on the cleavage surface, and the luster of the blocky ones is dull or slightly waxy. Transparent to translucent. The cleavage parallel to (0001) is not complete. The fractured crystals are shell-shaped; the massive ones are flaky, jagged, and sometimes earthy. Brittle in nature. It has a sour taste.

A complex salt of potassium sulfate and aluminum sulfate containing water of crystallization. At 20 degrees and 1 standard atmosphere, the solubility of alum in water is about 5.90g. It loses 9 molecules of crystal water at 64.5℃ and 12 molecules of crystal water at 200℃. It is slowly soluble in glycerol, soluble in water, and insoluble in ethanol and acetone.

When dissolved in water, it undergoes hydrolysis to form a colloidal precipitate of aluminum hydroxide. When heated, it loses its crystal water and becomes white powder (burnt alum).

Chemical composition: Alunite is alkaline potassium aluminum sulfate [KAl3(SO4)2(OH)6], which contains 11.4% potassium oxide (K2O), 37.0% aluminum oxide (Al2O3), 38.6% sulfur trioxide (SO3), and 13.0% water (H2O).

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