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Hydrated Lime Powder


Calcium hydroxide, commonly referred to as slaked lime, is described by the chemical formula Ca(OH)2. It is an inorganic compound which has a white, powdery appearance in its solid-state. However, Ca(OH)2 has a colourless appearance in its crystalline form.

The alternate names of this compound include hydrated lime, slack lime, pickling lime, and caustic lime. Generally, calcium hydroxide is prepared by mixing water and calcium oxide (also known as quick lime).

The chemical reaction between sodium hydroxide and calcium chloride dissolved in water (aqueous CaCl2) also yields this compound. The structure of a Ca(OH)2 molecule is illustrated below.


Physical & Chemical Properties
pH: 12-13
Specific Gravity: 1.5-5
Calcium Hydroxide: 80-95% (Test based on ASTM 311 Standards)
Colour: White
Form: Powder / Fine Particles

Physical Properties

  • Ca(OH)2 has a hexagonal crystal structure.
  • It is not very soluble in water and its solubility reduces with an increase in temperature. For example, its solubility at 0oC is 1.89 g/L and its solubility is 1.73 g/L at 20o
  • At temperatures approaching its melting point, this compound tends to lose water and decompose.
  • The solubility product (Ksp) of calcium hydroxide is 5.5 * 10-6.