Calcium hydroxide, commonly known as hydrated lime or hydrated lime, is an inorganic alkaline compound with the chemical formula Ca (OH) 2 and a molecular weight of 74.09. At room temperature, it is a white powdery solid with a density of about 2.24g/cm3. It is insoluble in water (1.73g/L, 20 ℃), insoluble in alcohol, soluble in glycerol and acid, and releases a large amount of heat when dissolved in acid. The pH of the saturated aqueous solution of calcium hydroxide is 12.4 (25 ℃). Calcium hydroxide decomposes into calcium oxide and water at 580 ℃. It can react with acids and acidic oxides to form corresponding acid salts and water, and react with salts to form new salts and bases, alkaline oxides, or ammonia gas.

physical property:

Density (g/mL, 25/4 ℃): 2.24

Calcium hydroxide is a fine white powder at room temperature, slightly soluble in water. Its clear aqueous solution is commonly known as clear lime water, and the emulsion suspension composed of water is called lime milk. And the solubility decreases with increasing temperature. Insoluble in alcohols, soluble in ammonium salts and glycerol, able to react with acids to generate corresponding calcium salts. At 580 ℃, it decomposes into calcium oxide and water.

chemical property:

alkaline

Calcium hydroxide is a strong alkali that has a corrosive effect on the skin and fabrics. But due to its low solubility, the degree of harm is not as great as strong bases such as sodium hydroxide. Calcium hydroxide can react with acid-base indicators:

Purple litmus test solution appears blue when encountering calcium hydroxide, while colorless phenolphthalein test solution appears red when encountering calcium hydroxide.