Calcium Hydroxide

Calcium hydroxide slaked lime is roughly made of lime after processed and refined to remove hazard matter like metallic matter.

Calcium Hydroxide Description:

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, 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.

Calcium Hydroxide Properties

When heated to 512 °C, the partial pressure of water in equilibrium with calcium hydroxide reaches 101 kPa (normal atmospheric pressure), which decomposes calcium hydroxide into calcium oxide and water.


Ca(OH)2 → CaO + H2O

A suspension of fine calcium hydroxide particles in water is called milk of lime. The solution is called limewater and is a medium strength base that reacts with acids and attacks many metals. Limewater turns milky in the presence of carbon dioxide due to formation of calcium carbonate, a process called carbonatation:

Ca(OH)2 + CO2 → CaCO3 + H2O

Structure, preparation, occurrence

Calcium hydroxide adopts a polymeric structure, as do the related hydroxides of the alkaline earth metals. The packing resembles the cadmium iodide motif with layers of octahedral Ca centres. Strong hydrogen bonds exist between the layers.The structure of calcium hydroxide, with the hydrogen atoms omitted (purple = O centres).

Calcium hydroxide is produced commercially by treating lime with water:

   CaO + H2O → Ca(OH)2

In the laboratory it can be prepared by mixing aqueous solutions of calcium chloride and sodium hydroxide. The mineral form, portlandite, is relatively rare but can be found in some volcanic, plutonic, and metamorphic rocks. It has also been known to arise in burning coal dumps.

Calcium Hydroxide Uses

One significant application of calcium hydroxide is as a flocculant, in water and sewage treatment. It forms a fluffy charged solid that aids in the removal of smaller particles from water, resulting in a clearer product. This application is enabled by the low cost and low toxicity of calcium hydroxide. It is also used in fresh water treatment for raising the pH of the water so pipes will not corrode where the base water is acidic because it is self-regulating and does not raise the pH too much.Another large application is in the paper industry, where it is used in the production of sodium hydroxide. This conversion is a component of the Kraft process

Niche uses:Calcium hydroxide is produced on a large scale, is easily handled and is cheap. Numerous niche applications are in use,An ingredient in whitewash, mortar, and plaster.

Food industry:
clarify raw juice from sugarcane or sugar beets in the sugar industry
process water for alcoholic beverages and soft drinks
pickle cucumbers and other foods
make Chinese century eggs
make corn tortillas (it helps the corn flour (masa) bind together)
clear a brine of carbonates of calcium and magnesium in the manufacture of salt for food and pharmaceutical uses fortify (Ca supplement) fruit drinks, such as orange juice, and infant formula
aid digestion (used in India as paan, a mixture of areca nuts, calcium hydroxide and a variety of seeds wrapped in betel leaves)substitute for baking soda in making papadam.

Native American uses
In Spanish, calcium hydroxide is called cal. Corn cooked with cal (nixtamalization) becomes hominy (nixtamal), which significantly increases the bioavailability of niacin, and it is also considered tastier and easier to digest

Afghan uses
It is used in making naswar (also known as nass or niswar), a type of dipping tobacco made from fresh tobacco leaves, calcium hydroxide (chuna), and wood ash.It is consumed most in the Pathan diaspora, Afghanistan, Pakistan, India, Bangladesh and also in Sweden and Norway. Villagers also use calcium hydroxide to paint their mud houses in Afghanistan and Pakistan.

Health risks

Unprotected exposure to Ca(OH)2 can pose health risks, so should be limited. It can cause severe skin irritation, chemical burns, blindness, or lung damage