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Calcium Hydroxide

 
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Calcium hydroxide, traditionally called slaked lime, hydrated lime, or pickling lime, is a chemical compound
Chemical compound

A chemical compound is a Chemical substance consisting of two or more different chemical element Chemical bond together in a fixed mass ratio that can be split into simpler substances....
 with the chemical formula Ca
Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the earth's Crust ....
(OH
Hydroxide

In chemistry, hydroxide is the name for the Diatomic molecule anion OH-, consisting of oxygen and hydrogen atoms, usually derived from the Dissociation of a base ....
)2. It is a colourless crystal or white powder, and is obtained when calcium oxide
Calcium oxide

Calcium oxide , commonly known as burnt lime, Lime or quicklime, is a widely used chemical compound. It is a white, Caustic and alkaline crystalline solid at room temperature....
 (called lime or quicklime) is mixed, or "slaked" with water
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
. It can also be precipitated by mixing an aqueous solution of calcium chloride
Calcium chloride

Calcium chloride, CaCl2, is a common Salt . It behaves as a typical ionic halide, and is solid at room temperature. It has several common applications such as brine for refrigeration plants, ice and dust control on roads, and in concrete....
 and an aqueous solution of sodium hydroxide
Sodium hydroxide

Sodium hydroxide , also known as lye, caustic soda and sodium hydrate, is a caustic metallic Base . Sodium hydroxide forms a strong alkaline solution when dissolved in a solvent such as water, however, only the hydroxide ion is basic....
.






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Calcium hydroxide, traditionally called slaked lime, hydrated lime, or pickling lime, is a chemical compound
Chemical compound

A chemical compound is a Chemical substance consisting of two or more different chemical element Chemical bond together in a fixed mass ratio that can be split into simpler substances....
 with the chemical formula Ca
Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the earth's Crust ....
(OH
Hydroxide

In chemistry, hydroxide is the name for the Diatomic molecule anion OH-, consisting of oxygen and hydrogen atoms, usually derived from the Dissociation of a base ....
)2. It is a colourless crystal or white powder, and is obtained when calcium oxide
Calcium oxide

Calcium oxide , commonly known as burnt lime, Lime or quicklime, is a widely used chemical compound. It is a white, Caustic and alkaline crystalline solid at room temperature....
 (called lime or quicklime) is mixed, or "slaked" with water
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
. It can also be precipitated by mixing an aqueous solution of calcium chloride
Calcium chloride

Calcium chloride, CaCl2, is a common Salt . It behaves as a typical ionic halide, and is solid at room temperature. It has several common applications such as brine for refrigeration plants, ice and dust control on roads, and in concrete....
 and an aqueous solution of sodium hydroxide
Sodium hydroxide

Sodium hydroxide , also known as lye, caustic soda and sodium hydrate, is a caustic metallic Base . Sodium hydroxide forms a strong alkaline solution when dissolved in a solvent such as water, however, only the hydroxide ion is basic....
. The name of the natural, mineral form is portlandite. It is relatively rare mineral, known from some volcanic, plutonic and metamorphic rocks. It has also been known to arise in burning coal dumps.

When heated to 512 °C, the partial pressure
Partial pressure

In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture....
 of water in equilibrium with calcium hydroxide reaches 101 kPa and decomposes
Chemical decomposition

Chemical decomposition or analysis is the separation of a chemical compound into chemical element or smaller compounds. It is sometimes defined as the opposite of a chemical synthesis....
 into calcium oxide and water. A suspension of fine calcium hydroxide particles in water is called milk of lime. The solution is called lime water
Lime water

Lime water is the common name for Saturation calcium hydroxide solution. Its chemical formula is Ca2. Since calcium hydroxide is only sparsely soluble, i.e....
 and is a medium strength base that reacts violently with acid
Acid

An acid is traditionally considered any chemical compound that, when dissolved in water, gives a solution with a hydrogen ion Activity greater than in pure water, i.e....
s and attacks many metal
Metal

In chemistry, a metal is a chemical element whose atoms readily lose electrons to form positive ions , and form metallic bonds between other metal atoms and ionic bonds between nonmetal atoms....
s in presence of water. It turns milky if carbon dioxide
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 is passed through, due to precipitation of calcium carbonate
Calcium carbonate

Calcium carbonate is a chemical compound with the chemical formula CalciumCarbonOxygen3. It is a common substance found as Rock in all parts of the world, and is the main component of seashells, snails, and eggshells....
.

Uses

Because of its strong basic properties, calcium hydroxide has many and varied uses:
  • A flocculant
    Flocculation

    Flocculation is a process where a solute comes out of solution in the form of floc or flakes. The action differs from Precipitation in that the solute coming out of solution does so at a concentration generally below its solubility limit in the liquid....
    , in water and sewage treatment
    Sewage treatment

    Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic....
     and improvement of acid soils
  • An ingredient in whitewash
    Whitewash

    Whitewash, or calcimine, kalsomine, or calsomine is a very low cost type of paint made from slaked lime and chalk . Various other additives have also been used....
    , mortar
    Mortar (masonry)

    Mortar is a workable paste formed by mixture of cement, water and fine aggregate masonry to bind construction blocks together and fill the gaps between them....
    , and plaster
    Plaster

    The term plaster can refer to plaster of Paris, lime plaster, or cement plaster. This article deals mainly with plaster of Paris.Plaster of Paris is a type of building material based on calcium sulfate Hydrate, nominally CaSO4?0.5H2O....
  • An alkali
    Alkali

    In chemistry, an alkali is a Base , Ionic compound salt of an alkali metal or alkaline earth metal Chemical element. Alkalis are best known for being Base s that dissolve in water....
     used as a lye
    Sodium hydroxide

    Sodium hydroxide , also known as lye, caustic soda and sodium hydrate, is a caustic metallic Base . Sodium hydroxide forms a strong alkaline solution when dissolved in a solvent such as water, however, only the hydroxide ion is basic....
     substitute in no-lye hair relaxer
    Relaxer

    A relaxer is a type of lotion or cream which hair straightening by chemically "relaxing" the natural curls. The active agent is usually a strong alkali, although some formulations are based on ammonium thioglycolate instead....
    s
  • A chemical depilatory
    Chemical depilatory

    A chemical depilatory is a cosmetic preparation used to remove the hair from the skin on the human body. Currently, a common active ingredient is Thioglycolic acid, which breaks down the disulfide bonds in keratin and weakens the hair so that it is easily scraped off where it emerges from the hair follicle....
     agent found in Nair
  • A Calcium supplement in mineral fortified baby formulas
  • A chemical reagent
    Reagent

    A reagent or reactant is a substance or compound consumed during a chemical reaction. Solvents and catalysts, although they are involved in the reaction, are usually not referred to as reactants....
    • In Bordeaux mixture
      Bordeaux mixture

      Bordeaux mixture is a mixture of copper sulfate and hydrated lime used as a fungicide in vineyards. It is used mainly to control garden, vineyard, nursery and farm infestations of fungus, primarily downy mildew which can result from infections of Plasmopara viticola....
       to neutralise the solution and form a long lasting fungicide.
    • In the reef aquarium
      Reef aquarium

      Marine aquaria include "fish only" tanks, "fish only with live rock" tanks, and "reef tanks". Fish only tanks often showcase large or aggressive marine fish species and generally rely on mechanical and chemical filtration....
       hobby for adding bio-available calcium in solution for calcium-using animals such as algae
      Algae

      Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds....
      , snails, hard tube worm
      Tube worm

      The name tube worm may refer to any of a number of unrelated tube-dwellingworm-like invertebrates.These include chiefly various polychaetes, specifically the Family Siboglinidae , Serpulidae, and related families of the order Canalipalpata....
      s, and Corals (often referred to as Kalkwasser
      Lime water

      Lime water is the common name for Saturation calcium hydroxide solution. Its chemical formula is Ca2. Since calcium hydroxide is only sparsely soluble, i.e....
       mix), and also to increase the alkalinity of the water.
    • In the tanning
      Tanning

      Tanning is the process of making leather, which does not easily Decomposition, from the skins of animals, which do. Often this uses tannin, an acidic chemical compound....
       industry for neutralization of acid
      Acid

      An acid is traditionally considered any chemical compound that, when dissolved in water, gives a solution with a hydrogen ion Activity greater than in pure water, i.e....
      , the liming of hides and skins and the flocculation of wastewater.
    • In the petroleum refining industry for the manufacture of additive
      Additive

      Additive may refer to:* Additive function, a function which preserves addition* Additive inverse, an arithmetic concept* Additive category, a Preadditive_category with finite Biproduct...
      s to oils (salicatic, sulphatic, fenatic)
    • In the chemical industry for manufacture of calcium stearate
      Stearic acid

      Stearic acid or 18:0 is a saturated fatty acid. It is a waxy solid, and its chemical formula is C18H36O2....
    • In the food industry
      Food industry

      The food industry is the complex, global collective of diverse businesses that together supply much of the food energy consumed by the world population....
       for processing water (for alcoholic
      Alcoholic beverage

      An alcoholic beverage is a drink containing ethanol . Alcoholic beverages are divided into three general classes: beers, wines, and distilled beverage....
       and soft drink
      Soft drink

      A soft drink is a beverage that does not contain alcohol. Carbonated soft drinks are commonly known as soda, soda pop, pop, coke or tonic in various parts of the United States, pop in Canada, fizzy drinks in the United Kingdom and Australia and sometimes minerals in Ireland....
      s)
    • Used in the separation of sugar from sugar cane in the sugar industry.
    • Used in the processing of Norwegian leutefisk. Dried cod fish is soaked in a mixture of slaked lime and soda to produce a soft-fleshed fish fillet that is steamed or baked and served with potato lefse.
    • For clearing a brine
      Brine

      File:Kissingen-Solepumpe-1848.JPGFile:Kissingen-Solepumpe-1848-2.JPGBrine is water Saturation or nearly saturated with a Salt .It is used to preserve vegetables, fish, and meat, in a process known as brining ....
       of carbonates of calcium and magnesium
      Magnesium

      Magnesium is a chemical element with the symbol Mg, atomic number 12, atomic weight 24.3050 and common oxidation number +2.Magnesium, an alkaline earth metal, is the ninth most abundance of the chemical elements in the universe by mass....
       in the manufacture of salt for food and pharmacopoeia
    • In Native American
      Indigenous peoples of the Americas

      The indigenous peoples of the Americas are the pre-Columbian inhabitants of the Americas, their descendants, and many ethnic groups who identify with those peoples....
       and Latin American cooking, calcium hydroxide is called "cal". Corn cooked with cal becomes nixtamal
      Nixtamalization

      Nixtamalization typically refers to a process for the preparation of maize in which the grain is soaked and cooking in an alkaline solution, usually Lime water, and hulling....
       which significantly increases its nutrition value, and is also considered tastier and easier to digest.
    • In chewing Betel nut
      Betel nut

      The Areca nut is the seed of the Areca palm , which grows in much of the tropical Pacific, Asia, and parts of east Africa.The areca nut is not a true nut but rather a drupe....
       or coca leaves, calcium hydroxide is usually chewed alongside to keep the alkaloid
      Alkaloid

      Alkaloids are naturally occurring chemical compounds containing base nitrogen atoms. The name derives from the word alkaline and was used to describe any nitrogen-containing base....
       stimulant
      Stimulant

      Stimulant drugs are drugs that temporarily increase alertness and awareness. They usually have increased side-effects with increased effectiveness, and the more powerful variants are therefore often prescription medicines or illegal drugs....
      s chemically available for absorption by the body
    • Similarly, Native Americans
      Indigenous peoples of the Americas

      The indigenous peoples of the Americas are the pre-Columbian inhabitants of the Americas, their descendants, and many ethnic groups who identify with those peoples....
       traditionally chewed tobacco leaves with calcium hydroxide derived from burnt shells to enhance the effects
  • A filler
    • In the petrochemical
      Petrochemical

      Petrochemicals are chemical products made from raw materials of petroleum or other hydrocarbon origin. Although some of the chemical compounds that originate from petroleum may also be derived from coal and natural gas, petroleum is the major source....
       industry for manufacturing solid oil of various marks
    • In the manufacture of brake pad
      Brake

      A brake is a device for applying a force against the friction of the road, slowing or stopping the motion of a machine or vehicle, or alternatively a device to restrain it from starting to move again....
      s
    • In the manufacture of ebonite
      Ebonite

      Ebonite is a very hard rubber first obtained by Charles Goodyear by vulcanization rubber for prolonged periods. It is about 30% to 40% sulfur.Its name comes from its intended use as an artificial substitute for ebony wood....
    • For preparation of dry mixes for paint
      Paint

      Paint is any liquid, liquifiable, or mastic composition which after application to a Substrate in a thin layer is converted to an opaque solid film....
      ing and decorating
    • In manufacturing mixes for pesticide
      Pesticide

      A pesticide is a substance or mixture of substances used to kill a pest .A pesticide may be a chemical substance, biological agent , antimicrobial, disinfectant or device used against any pest ....
      s
    • In manufacturing the trademarked compound "Polikar", an antifungal and antimicrobial
      Antimicrobial

      An antimicrobial is a substance that kills or inhibits the growth of microbes such as bacteria, fungi, protozoals or viruses. Antimicrobial drugs either kill microbes or prevent the growth of microbes ....
       preservative for vegetable
      Vegetable

      The term "vegetable" generally means the Eating parts of plants. The definition of the word is traditional rather than scientific, however, and therefore the usage of the word is somewhat arbitrary and subjective, as it is determined by individual cultural customs of food selection and food preparation....
      s in storage
  • In Dentistry, it is used as dressing in paste form used for anti-microbial effect during a dental
    Dentistry

    Dentistry is the known evaluation, diagnosis, prevention, and treatment of diseases, disorders and conditions of the mouth, maxillofacial area and the adjacent and associated structures and their impact on the human body....
     root canal
    Root canal

    A root canal is the space within the root of a tooth. It is part of a naturally occurring space within a tooth that consists of the pulp chamber , the main canal, and more intricate anatomical branches that may connect the root canals to each other or to the surface of the root....
     procedure. Calcium hydroxide is known to have a strong anti-microbial effect and is a bone-regeneration stimulant.
  • It has been proposed to add it to sea water in great quantities to reduce atmospheric CO2
    Carbon dioxide

    Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
     and fight the greenhouse effect
    Greenhouse effect

    The greenhouse effect refers to the change in the steady state temperature of a planet or moon by the presence of an atmosphere containing gas that absorbs and emits infrared....
    • Used as an acid suppressor in the production of metals. Lime is injected into the waste gas stream to neutralise acids such as fluorides and chlorides prior to being released to atmosphere


Health risks

As with many chemicals, exposure may pose health risks:
  • Inhalation: Respiratory tract irritation. Coughing, shortness of breath, chemical bronchitis.
  • Ingestion: Internal bleeding
    Internal bleeding

    Internal bleeding is bleeding occurring inside the body. It can be a serious medical emergency depending on where it occurs , and can potentially cause death and cardiac arrest if proper medical treatment is not received quickly....
    , possible perforation of esophagus, severe pain, vomiting, diarrhea, and collapse.
  • Eyes: severe irritation, pain, ulceration, blindness.
  • Skin: burns, blistering.
  • Chronic Exposure: dermatitis or severe irritation to skin.


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