Calcium hydroxide

CAS Number: 1305-62-0
Chemical Formula:  CaH2O2
Synonyms:
CALCIUMHYDROXIDE,POWDER,REAGENT,ACS
CALCIUMHYDROXIDE,POWDER,USP,EP,BP,JP
Calcium Hydroxide, Powder, Reagent
Appearance: White Powder
MOQ (Minimum Order Quantity): 1 FCL (Full Container Load)

Product Details

Calcium hydroxide is a colorless crystal or white powder formed when calcium oxide (lime or quicklime) reacts with water in a slaking process. It can also be produced by precipitation from calcium chloride and sodium hydroxide solutions. The natural mineral form is called portlandite, a relatively rare mineral found in certain volcanic, plutonic, and metamorphic rocks, as well as in coal combustion deposits.

Parameters

PropertyValue
Melting point580 °C
Boiling point2850 °C
density2.24 g/mL at 25 °C (lit.)
bulk density400 kg/m³
refractive index1.574
storage temp.Store at +5°C to +30°C
solubility1.7 g/L
formSolid
pKa12.6 [at 20 ℃]
colorWhite
OdorOdorless
PH Range12.4
PH11.27 (1 mM solution); 12.2 (10 mM solution); 12.46 (100 mM solution)
Water Solubility1.65 g/L (20 ºC)
SensitiveAir Sensitive
Merck14,1673
Solubility Product Constant (Ksp)pKsp: 5.26
Exposure limitsACGIH: TWA 5 mg/m³; OSHA: TWA 15 mg/m³; TWA 5 mg/m³; NIOSH: TWA 5 mg/m³
StabilityStable. Incompatible with strong acids.
Cosmetics Ingredients FunctionsBUFFERING
CAS DataBase Reference1305-62-0 (CAS DataBase Reference)
NIST Chemistry ReferenceCalcium dihydroxide (1305-62-0)
EPA Substance Registry SystemCalcium hydroxide (1305-62-0)

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PropertyValue
Melting point580 °C
Boiling point2850 °C
density2.24 g/mL at 25 °C (lit.)
bulk density400 kg/m³
refractive index1.574
storage temp.Store at +5°C to +30°C
solubility1.7 g/L
formSolid
pKa12.6 [at 20 ℃]
colorWhite
OdorOdorless
PH Range12.4
PH11.27 (1 mM solution); 12.2 (10 mM solution); 12.46 (100 mM solution)
Water Solubility1.65 g/L (20 ºC)
SensitiveAir Sensitive
Merck14,1673
Solubility Product Constant (Ksp)pKsp: 5.26
Exposure limitsACGIH: TWA 5 mg/m³; OSHA: TWA 15 mg/m³; TWA 5 mg/m³; NIOSH: TWA 5 mg/m³
StabilityStable. Incompatible with strong acids.
Cosmetics Ingredients FunctionsBUFFERING
CAS DataBase Reference1305-62-0 (CAS DataBase Reference)
NIST Chemistry ReferenceCalcium dihydroxide (1305-62-0)
EPA Substance Registry SystemCalcium hydroxide (1305-62-0)

Product Application

As a strong alkaline substance, calcium hydroxide serves as a pharmaceutical pH adjuster, buffer, and antacid in topical ointments, creams, lotions, and suspensions, often used in the form of lime water. It reacts with fatty acids to form calcium soaps that stabilize water‑in‑oil emulsions such as calamine liniment, and also acts as a topical astringent.

It is widely used in cosmetics, including hair straightening, hair removal, and shaving products.

In dentistry, it is applied as a filling material and in dental pastes to promote the formation of secondary dentine. Traditionally, it was used as an escharotic agent in Vienna Paste.

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