Calcium hydroxide is a white powdery solid. The chemical formula Ca (OH) 2, commonly known as hydrated lime or quicklime, forms two layers after adding water. The upper aqueous solution is called clear lime water, and the lower suspension is called lime milk or lime slurry. The upper clear liquid lime water can detect carbon dioxide, while the lower turbid liquid lime milk is a building material. Calcium hydroxide is a binary medium strong alkali (calcium hydroxide is considered a strong alkali in secondary school, but in reality it cannot be completely ionized in water, so it is considered a medium strong alkali in university textbooks), with alkaline properties and corrosive effects on skin and fabrics. Calcium hydroxide has a wide range of applications in industry. It is a commonly used building material, as well as used as a fungicide and chemical raw material.

1. Can be used as a raw material for producing calcium carbonate.

2. Calcium hydroxide is alkaline and can be used to reduce soil acidity, thereby improving soil structure. Bordeaux mixture in pesticides is prepared by mixing lime milk (calcium hydroxide dissolved in water) and copper sulfate aqueous solution in a certain proportion. In winter, trees are protected against insects by applying 80 cm of lime slurry above the roots.

3. Youpin is mainly used for the production of epichlorohydrin and epichlorohydrin.

4. It can be used in rubber and petrochemical additives, such as adding it to lubricating oil in the petroleum industry, to prevent coking, sludge deposition, neutralization and corrosion prevention.

5. Used for producing bleaching powder, bleaching powder essence, disinfectant, acid making agent, astringent, hard water softener, soil acidity inhibitor, depilatory agent, buffering agent, neutralizing agent, curing agent, etc.

6. Calcium hydroxide reacts with carbon dioxide in the air to form insoluble calcium carbonate. In the sugar industry production, calcium hydroxide is first used to neutralize the acid in the syrup, and then carbon dioxide is introduced to react with the remaining calcium hydroxide to produce a precipitate that is filtered out to reduce the acidity of the sugar.