Calcium hydroxide: Difference between revisions

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'''Calcium Hydroxide''' 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]] (also called 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, where it is an ingredient in the process of making corn tortillas.
{{Short description|Chemical compound}}
{{Use dmy dates|date=October 2023}}


==Chemical Properties==
'''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]] (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, construction, and chemical processes.
Calcium hydroxide is a soft white powdery substance with a slight earthy smell and an alkaline taste. It is insoluble in alcohol but slightly soluble in water to give a solution known as [[lime water]]. When heated to 512°C, the partial pressure of water in equilibrium with calcium hydroxide reaches 101 kPa (standard atmospheric pressure), which decomposes calcium hydroxide into [[calcium oxide]] and water.


==Uses==
==Properties==
Calcium hydroxide has a wide variety of uses, including as a pH modifier in industrial wastewater control and as a reagent in flue gas desulfurization. It is also used in the production of [[mortar]] that is used in construction and maintenance of buildings. In food preparation, it is used in the process of making corn tortillas, and in the process of making sugar from sugar beets.
Calcium hydroxide is a soft, white, powdery solid with a slightly bitter taste. It is sparingly soluble in water, with a solubility of about 1.5 g/L at 25 °C. The solution is called lime water, and it is a medium strength base that reacts with acids to form salts. The solubility decreases with increasing temperature, which is unusual for most salts.
 
[[File:Calcium_hydroxide.jpg|Calcium hydroxide|thumb|right]]
 
==Production==
Calcium hydroxide is produced by mixing [[calcium oxide]] (CaO) with water in a process called slaking:
 
:CaO + H₂O → Ca(OH)₂
 
This reaction is exothermic and releases heat. The resulting product is a fine white powder that is used in various applications.
 
==Applications==
 
===Construction===
In the construction industry, calcium hydroxide is used as a key ingredient in [[mortar]] and [[plaster]]. It is also used in the production of [[concrete]] and as a pH modifier in soil stabilization.
 
===Food Industry===
Calcium hydroxide is used in the food industry for processing [[corn]] into [[nixtamal]], which is used to make [[tortillas]] and [[tamales]]. This process, known as [[nixtamalization]], improves the nutritional value of the corn and enhances its flavor.
 
[[File:Nixtamalized_Corn_maize_El_Salvador_recipe.jpg|Nixtamalized corn, a process involving calcium hydroxide|thumb|left]]
 
===Chemical Industry===
In the chemical industry, calcium hydroxide is used as a pH regulator and as a source of calcium ions. It is also used in the production of [[calcium salts]] and as a flocculant in water and sewage treatment.
 
===Other Uses===
Calcium hydroxide is used in the [[leather]] industry for dehairing hides and in the [[paper]] industry for pulp production. It is also used in the [[sugar]] industry to purify raw sugar.


==Safety==
==Safety==
Calcium hydroxide is not considered very toxic. However, prolonged contact with skin or eyes can cause severe irritation. If swallowed, it can cause severe digestive discomfort. It is always recommended to handle calcium hydroxide with appropriate safety equipment.
Calcium hydroxide is considered to be a low hazard material, but it can cause skin irritation and eye damage upon contact. It is important to handle it with care and use appropriate protective equipment.


==See Also==
==Related pages==
* [[Calcium oxide]]
* [[Lime (material)]]
* [[Lime (material)]]
* [[Calcium oxide]]
* [[Nixtamalization]]
* [[Lime water]]
* [[Mortar (masonry)]]


[[Category:Chemical compounds]]
[[Category:Calcium compounds]]
[[Category:Calcium compounds]]
[[Category:Hydroxides]]
[[Category:Hydroxides]]
[[Category:Alkalis]]
[[Category:Food additives]]
{{Chemistry-stub}}
[[Category:Building materials]]
==Calcium_hydroxide==
<gallery>
File:CaOH2SEM.jpg|Scanning electron microscope image of calcium hydroxide
File:Nixtamalized_Corn_maize_El_Salvador_recipe.jpg|Nixtamalized corn, a process involving calcium hydroxide
File:Dying_Gaul_(casting_in_Pushkin_museum)_04_by_shakko.jpg|Sculpture casting, possibly related to calcium hydroxide in the casting process
</gallery>
<gallery>
File:Calcium_hydroxide.jpg|Calcium hydroxide
File:Mg(OH)2Xray.jpg|X-ray diffraction pattern of magnesium hydroxide
File:CaOH2SEM.jpg|Scanning electron microscope image of calcium hydroxide
File:Nixtamalized_Corn_maize_El_Salvador_recipe.jpg|Nixtamalized corn maize from El Salvador
File:Dying_Gaul_(casting_in_Pushkin_museum)_04_by_shakko.jpg|Dying Gaul sculpture casting in Pushkin museum
</gallery>

Latest revision as of 11:06, 23 March 2025

Chemical compound



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 (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, construction, and chemical processes.

Properties[edit]

Calcium hydroxide is a soft, white, powdery solid with a slightly bitter taste. It is sparingly soluble in water, with a solubility of about 1.5 g/L at 25 °C. The solution is called lime water, and it is a medium strength base that reacts with acids to form salts. The solubility decreases with increasing temperature, which is unusual for most salts.

Calcium hydroxide

Production[edit]

Calcium hydroxide is produced by mixing calcium oxide (CaO) with water in a process called slaking:

CaO + H₂O → Ca(OH)₂

This reaction is exothermic and releases heat. The resulting product is a fine white powder that is used in various applications.

Applications[edit]

Construction[edit]

In the construction industry, calcium hydroxide is used as a key ingredient in mortar and plaster. It is also used in the production of concrete and as a pH modifier in soil stabilization.

Food Industry[edit]

Calcium hydroxide is used in the food industry for processing corn into nixtamal, which is used to make tortillas and tamales. This process, known as nixtamalization, improves the nutritional value of the corn and enhances its flavor.

Nixtamalized corn, a process involving calcium hydroxide

Chemical Industry[edit]

In the chemical industry, calcium hydroxide is used as a pH regulator and as a source of calcium ions. It is also used in the production of calcium salts and as a flocculant in water and sewage treatment.

Other Uses[edit]

Calcium hydroxide is used in the leather industry for dehairing hides and in the paper industry for pulp production. It is also used in the sugar industry to purify raw sugar.

Safety[edit]

Calcium hydroxide is considered to be a low hazard material, but it can cause skin irritation and eye damage upon contact. It is important to handle it with care and use appropriate protective equipment.

Related pages[edit]