Ammonium sulfate

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  Ammonium sulfate crystal structure
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  3D molecular model of ammonium sulfate
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  Cotton balls

Ammonium Sulfate

Ammonium sulfate is an inorganic salt with the chemical formula (NH_)_SO_. It is commonly used as a fertilizer for alkaline soils. In the soil, the ammonium ion is released and forms a small amount of acid, lowering the pH balance of the soil, while contributing essential nitrogen for plant growth.

Chemical Properties

Ammonium sulfate is a white, odorless solid that is soluble in water. It has a melting point of 235 °C and decomposes before boiling. The compound is composed of two ammonium ions (NH__) and one sulfate ion (SO___). It is a typical ionic compound, and its solubility in water is 70.6 g/100 mL at 0 °C.

Production

Ammonium sulfate is produced by treating ammonia with sulfuric acid:

2 NH_ + H_SO_ _ (NH_)_SO_

This reaction is exothermic and is typically carried out in a reactor where ammonia gas is bubbled through a solution of sulfuric acid. The resulting ammonium sulfate precipitates out of the solution and is collected by filtration.

Uses

Fertilizer

The primary use of ammonium sulfate is as a fertilizer for alkaline soils. It provides two essential nutrients: nitrogen and sulfur. The nitrogen is in the form of ammonium ions, which are readily absorbed by plants. The sulfur is in the form of sulfate ions, which are also essential for plant growth.

Food Additive

Ammonium sulfate is used as a food additive, particularly in the baking industry. It acts as a dough conditioner and is recognized as safe by food safety authorities.

Laboratory Use

In the laboratory, ammonium sulfate is used for the precipitation of proteins. This process, known as "salting out," exploits the reduced solubility of proteins in high salt concentrations.

Safety

Ammonium sulfate is generally regarded as safe when handled properly. However, it can cause irritation to the eyes, skin, and respiratory tract. Proper protective equipment should be used when handling the compound.

Related Pages

• Ammonia
• Sulfuric acid
• Fertilizer
• Ionic compound