What is used in white washing walls?

It is Ca(OH)2 which is used for white washing.Ca(OH)2 is produced by reaction of CaO and water.

Ca(OH)2 is used for whitewashing walls as it slowly reacts with CO₂ in air to form CaCO3.It is hard and give a shiny finish to the walls.

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calcium hydroxide, Ca(OH)₂, colorless crystal or white powder. It is prepared by reacting calcium oxide (lime) with water, a process called slaking, and is also known as hydrated lime or slaked lime. When heated above 580°C it dehydrates, forming the oxide.
"Slaked lime" redirects here. For (Ca(OH)₂)_(aq), see limewater. For the application of slaked lime as a wall colorant, see limewash. Calcium hydroxide

Names IUPAC name Calcium hydroxide Other names

Slaked lime
Milk of lime
Caustic lime
Calcium(II) hydroxide
Pickling lime
Hydrated lime
Portlandite
Calcium hydrate

Identifiers CAS Number

1305-62-0

3D model (Jmol)

Interactive image
Interactive image

ChEBI

CHEBI:31341

ChemSpider

14094

ECHA InfoCard 100.013.762 EC Number 215-137-3 E number E526 (acidity regulators, ...) Gmelin Reference 846915 KEGG

D01083

PubChem CID

14777

RTECS number EW2800000 UNII

PF5DZW74VN

InChI[show] SMILES[show] Properties Chemical formula Ca(OH)₂ Molar mass 74.093 g/mol Appearance White powder Odor Odorless Density 2.211 g/cm³, solid Melting point 580 °C (1,076 °F; 853 K) (loses water, decomposes) Solubility in water

1.89 g/L (0 °C)
1.73 g/L (20 °C)
0.66 g/L (100 °C)

Solubility product (K_sp) 5.5×10⁻⁶ Solubility

Soluble in glycerol and acids.
Insoluble in alcohol.

Basicity (pK_b) 1.37 (first OH⁻), 2.43 (second OH⁻)^[1]^[2] Magnetic susceptibility (χ) −22.0·10⁻⁶ cm³/mol Refractive index (n_D) 1.574 Structure Crystal structure Hexagonal, hP3^[3] Space group P3m1 No. 164 Lattice constant a = 0.35853 nm, c = 0.4895 nm Thermochemistry Std molar
entropy (S^o₂₉₈) 83 J·mol⁻¹·K⁻¹^[4] Std enthalpy of
formation (Δ_fH^o₂₉₈) −987 kJ·mol⁻¹^[4] Hazards Safety data sheet See: data page
^[5] R-phrases R22, R34 S-phrases (S2), S24 NFPA 704

0 3 0 Flash point Non-flammable Lethal dose or concentration (LD, LC): LD₅₀ (median dose) 7340 mg/kg (oral, rat)
7300 mg/kg (mouse) US health exposure limits (NIOSH): PEL (Permissible) TWA 15 mg/m³ (total) 5 mg/m³ (resp.)^[6] REL (Recommended) TWA 5 mg/m³^[6] IDLH (Immediate danger) N.D.^[6] Related compounds Other cations Magnesium hydroxide
Strontium hydroxide
Barium hydroxide Related bases Calcium oxide Supplementary data page Structure and
properties Refractive index (n),
Dielectric constant (ε_r), etc. Thermodynamic
data Phase behaviour
solid–liquid–gas Spectral data UV, IR, NMR, MS Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca(OH)₂. It is a colorless crystal or white powder and is obtained when calcium oxide (called lime or quicklime) is mixed, or slaked with water. It has many names including hydrated lime, caustic lime, builders' lime, slack lime, cal, or pickling lime. Calcium hydroxide is used in many applications, including food preparation. Limewater is the common name for a saturated solution of calcium hydroxide.