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Calcium oxide

Chemical properties Uses Content analysis Identification test Toxicity Production method Usage limitation Hazards & Safety Information
Calcium oxide
Calcium oxide
Chemical Name:
Calcium oxide
Molecular Formula:
Formula Weight:
MOL File:

Calcium oxide Properties

Melting point:
2570 °C
Boiling point:
2850 °C(lit.)
3.3 g/mL at 25 °C(lit.)
refractive index 
Flash point:
storage temp. 
Store at RT.
1.65g/l Risk of violent reaction.
White to yellow-very slightly beige
12.6 (H2O, 20℃)(saturated solution)
Water Solubility 
Air & Moisture Sensitive
Stability Stable, but absorbs carbon dioxide from the air. Incompatible with water, moisture, fluorine, strong acids.
CAS DataBase Reference
1305-78-8(CAS DataBase Reference)
NIST Chemistry Reference
Calcium monoxide(1305-78-8)
EPA Substance Registry System
Calcium oxide (CaO)(1305-78-8)
  • Risk and Safety Statements
  • Hazard and Precautionary Statements (GHS)
Hazard Codes  C,Xi
Risk Statements  34-41-37/38
Safety Statements  26-36/37/39-45-25-39
RIDADR  1910
WGK Germany  1
RTECS  EW3100000
HazardClass  8
PackingGroup  III
HS Code  28259019
Hazardous Substances Data 1305-78-8(Hazardous Substances Data)
Signal word: Danger
Hazard statements:
Code Hazard statements Hazard class Category Signal word Pictogram P-Codes
H315 Causes skin irritation Skin corrosion/irritation Category 2 Warning P264, P280, P302+P352, P321,P332+P313, P362
H318 Causes serious eye damage Serious eye damage/eye irritation Category 1 Danger P280, P305+P351+P338, P310
H335 May cause respiratory irritation Specific target organ toxicity, single exposure;Respiratory tract irritation Category 3 Warning
Precautionary statements:
P261 Avoid breathing dust/fume/gas/mist/vapours/spray.
P280 Wear protective gloves/protective clothing/eye protection/face protection.
P304+P340 IF INHALED: Remove victim to fresh air and Keep at rest in a position comfortable for breathing.
P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.
P405 Store locked up.

Calcium oxide price More Price(28)

Manufacturer Product number Product description CAS number Packaging Price Updated Buy
Sigma-Aldrich 1.02109 Calcium oxide from marble small lumps ~3-20 mm 1305-78-8 1EA $109 2017-11-08 Buy
Sigma-Aldrich 1.02109 Calcium oxide from marble small lumps ~3-20 mm 1305-78-8 2EA $1500 2017-11-08 Buy
Alfa Aesar 10684 Calcium oxide, Puratronic?, 99.998% (metals basis, excluding other alkaline earth and alkali metals 130ppm max) 1305-78-8 1g $0 2017-11-08 Buy
Alfa Aesar 10684 Calcium oxide, Puratronic?, 99.998% (metals basis, excluding other alkaline earth and alkali metals 130ppm max) 1305-78-8 2g $38.1 2017-11-08 Buy
Strem Chemicals 20-2030 Calcium oxide (99.95%-Ca) 1305-78-8 50g $88 2017-11-27 Buy

Calcium oxide Chemical Properties,Uses,Production

Chemical properties

It appears as white cubic crystalline powder. Industrial products often contain magnesia, alumina and ferric oxide and other impurities so exhibit dark gray, light yellow or brown. It is soluble in acid.


1.  Calcium oxide can be used in the manufacture of calcium carbide, soda ash, bleaching powder, used as building materials, refractoriness’, desiccant and soil conditioner and calcium fertilizer
2.  It can be used as an analysis reagent and flux agent for manufacturing fluorescence powder.
3.  It can be used in the manufacture of calcium carbide, soda ash, bleaching powder, also used for leather, waste water purification
4.  Calcium oxide can be used as building materials, metallurgical flux agent and the major raw materials for the manufacturing of calcium hydroxide and a variety of calcium compounds. It is also the inexpensive alkali in the chemical industry. It is widely used in pesticides, paper, food, petrochemical, leather, waste water purification and so on. It can also be used for the drying of the laboratory ammonia and alcohol dehydration.
5.  Use as drug carriers.
6.  Uses as analysis reagents; Calcium oxide can be applied to steel, pesticides, pharmaceuticals, non-ferrous metals, fertilizers, leather and manufacturing of calcium hydroxide, drying of laboratory ammonia, carbon dioxide absorbent and alcohol dehydration.

Content analysis

Approximately 1 g of the sample was burned to constant weight (accurately weighed) and dissolved in 20 ml of dilute hydrochloric acid solution (TS-117). After cooling, dilute to 500.0ml with water and mix uniformly. Take 50 mL of this solution into the appropriate container, add 50ml of water. Add 30 mL 0.05ml/L disodium EDTA via a 50 mL burette with stirring (preferably with a magnetic stirrer); further add 15ml sodium hydroxide solution (TS-224) and hydroxy naphthol blue indicator (300 mg) for continue titration to the blue end. Per ml of 0.05 mol/L of EDTA corresponds to 2.804 mg of calcium oxide.

Identification test

1 g of the sample was shaken with 20 ml of water, and the acetic acid test solution (TS-1) was added to dissolve the sample. The calcium test (IT-10) of this solution was positive.


ADI is not subject to restrictive regulations (FAO/WHO, 2001).
GRAS (FDA, §18.5210; §184.12l0, 2000);
See Calcium Oxide.
It can stimulate the mucous membrane, causing sneezing, in particular, can cause fat saponification so the water will be absorbed by the skin, dissolving the protein with stimulating and corroding the tissue. It has strong effect against the eye mucosa, being able cause oral and nasal mucosa superficial ulcers, and sometimes there may be perforation of the nasopharyngeal diaphragm, deep respiratory tract disease. Inhalation of lime dust may cause pneumonia.
In case of inhalation of dust, it can be treated via inhaling water vapor (add some of the citric acid crystals to the water in advance) and coat the mustard cream in the chest. If falling into the eyes, we can open up the eyes and immediately rinse with running water for 10~30 min and then rinse with 5% ammonium chloride solution. When the skin burns, it can be used with 5% citric acid, tartaric acid, acetic acid or salt solution of mineral oil or vegetable oil to remove the lime residue sticking to the skin.
The maximum allowable concentration in the United States is 5 mg/m3.
During operation, it should be paid attention to the protection of respiratory organs. Wear uniforms manufactured using dust-proof fiber, gloves and closed dust-proof glasses. Coat the ointment-containing grease. Clean after work. During the preparation and application, it should be prevented of dust inhalation.

Production method

Calcium carbonate calcination first apply calcium carbonate for reaction with hydrochloric acid to generate calcium chloride, followed by addition of ammonia for neutralization, standing for precipitation and filtration, followed by adding sodium bicarbonate for reaction to generate calcium carbonate precipitate. It is further subject to centrifugal separation dehydration, drying and calcination, followed by crushing and screening to obtain the finished product of medicinal calcium oxide. Its reaction is:
CaCO3 + 2HCl → CaCl2 + CO2 + H2O
CaCl2 + 2NH3? H2O? Ca (OH) 2 + 2NH4Cl
Ca (OH) 2 + NaHCO3 → CaCO3 + NaOH + H2O
CaCO3 [△]→CaO + CO2 ?.
Limestone calcination method: crush the coarse limestone to 150 mm, and screen for the fine residue below 30 to 50 mm. Anthracite or coke required a particle size to be below 50 mm, which contains not too much low melting point ash content. The amount of anthracite or coke is 7.5% to 8.5% of that of limestone by weight. The selected limestone and fuel are timely and quantitatively supplied from the kiln crown to the kiln, further calcinated at 900~1200 ℃ and then lead to the finished product after cooling. In the calcination process, carbon dioxide is produced as by-product. Its reaction equation is:
CaCO3 [△]→CaO + CO2 .

Usage limitation

GB 14880-94 (in terms of Ca, g/kg): beverages, cereals and their products, 1.6~3.2; infant food, 3.0~6.0.
GB 2760-2001: Preparation of water 100mg/L (36mg/L in terms of Ca).

Hazards & Safety Information

Category Corrosive items
Toxic classification poisoning
Acute toxicity Intraperitoneal-mouse LD50: 3059 mg/kg
Explosive and hazardous properties it is corrosive to the skin; powdered calcium oxide can be mixed with water to be explode; its mixture with alcohol can be flammable and explosive upon heating
Flammable hazardous characteristics exothermic upon water with its heat being able to cause organic combustion; one of the air pollutants with heating together with alcohol mixture being able to cause combustion
Storage and transportation characteristics Treasury: Ventilated, low temperature and drying; Store separately from combustible materials, acids and phosphorus pentoxide.
Fire extinguishing agent mist water, sand
Occupational Standard TLV-TWA 2 mg/m3; STEL 5 mg/m3


Calcium oxide (CaO, CAS Reg. No. 1305-78-8) is also known as lime, quick lime, burnt lime, or calx. Lime does not occur naturally since it reacts so readily with water (to form hydrated lime) and carbon dioxide (to form limestone). It is produced from calcium carbonate, limestone, or oyster shells by calcination at temperatures of 1,700-2,450℃.
Calcium Oxide is a solid with a very high affinity for water - it will react with water in the air, or in your skin or anywhere it can and form calcium hydroxide. This reaction is exothermic so it releases a lot of heat while it is reacting - there fore as well as being corrosive and causing significant skin irritation, calcium oxide's reaction with water can also cause burns. Calcium hydroxide is basically hydrated calcium oxide. It is alkali so can be corrosive. In solution it makes limewater.
CaO is not found pure in nature but rather is contained in various abundant minerals (i.e. calcite, aragonite, limestone, marble) but vary greatly in their purity (impurities usually include magnesia, iron, alumina, silica, sulfur). Of these iron and sulfur are most troublesome (i.e. where clarity is important in glass). Lime minerals vary in the degree of crystallization and cohesion of the crystalline mass and the homogeneity of the matrix.
Calcium oxide is the principle flux in medium and high temperature glazes, beginning its action (within the glaze) around 1100C. It must be used with care in high-fire bodies because its active fluxing action can produce a body that is too volatile (melting if slightly overfired).
Lime, or calcium oxide, is a principle ingredient in the production of Portland cement, the basis for most mortars and concrete. Hydrated or ‘slaked’ lime is the chemical calcium hydroxide. This chemical is also used in mortars. Both types of lime are strong bases and are also used in food production (calcium hydroxide is commonly used in making corn tortillas), petroleum refining and sewage treatment. In the household it is used by aquarium hobbyists to add bioavailable calcium to fish tanks. It is also found in hair relaxers.

Chemical Properties

white to grey solid


In bricks, plaster, mortar, stucco and other building and construction materials; manufacture of steel, aluminum, magnesium, and flotation of non-ferrous ores; manufacture of glass, paper, Na2CO3 (Solvay process), Ca salts and many other industrial chemicals; dehairing hides; clarification of cane and beet sugar juices; in fungicides, insecticides, drilling fluids, lubricants; water and sewage treatment; in laboratory to absorb CO2 (the combination with NaOH is known as soda-lime, q.v.).


ChEBI: A member of the class of calcium oxides of calcium and oxygen in a 1:1 ratio.

General Description

An odorless, white or gray-white solid in the form of hard lumps. A strong irritant to skin, eyes and mucous membranes. Used in insecticides and fertilizers.

Air & Water Reactions

Crumbles on exposure to moist air. Reacts with water to form corrosive calcium hydroxide, with evolution of much heat. Temperatures as high as 800° C have been reached with addition of water (moisture in air or soil). The heat of this reaction has caused ignition of neighboring quantities of sulfur, gunpowder, wood, and straw [Mellor 3: 673 1946-47].

Reactivity Profile

A base and an oxidizing agent. Neutralizes acids with generation of heat. Nonflammable, but will support combustion by liberation of oxygen, especially in the presence of organic materials. Reacts very violently with liquid hydrofluoric acid [Mellor 2, Supp. 1:129 1956]. Reacts extremely violently with phosphorus pentaoxide when reaction is initiated by local heating [Mellor 8 Supp.3:406 1971].

Health Hazard

Causes burns on mucous membrane and skin. Inhalation of dust causes sneezing.

Fire Hazard

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Vapors may accumulate in confined areas (basement, tanks, hopper/tank cars etc.). Substance will react with water (some violently), releasing corrosive and/or toxic gases and runoff. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water.

Calcium oxide Preparation Products And Raw materials

Raw materials

Preparation Products

Calcium oxide Suppliers

Global( 152)Suppliers
Supplier Tel Fax Email Country ProdList Advantage
Henan Tianfu Chemical Co.,Ltd.
0371-55170693 CHINA 20810 55
J & K SCIENTIFIC LTD. 400-666-7788 +86-10-82848833
+86-10-82849933; China 96820 76
Meryer (Shanghai) Chemical Technology Co., Ltd. +86-(0)21-61259100(Shanghai) +86-(0)755-86170099(ShenZhen) +86-(0)10-62670440(Beijing)
+86-(0)21-61259102(Shanghai) +86-(0)755-86170066(ShenZhen) +86-(0)10-88580358(Beijing) China 40398 62
Alfa Aesar 400-610-6006; 021-67582000
021-67582001/03/05 China 30309 84
Beijing dtftchem Technology Co., Ltd. 13651141086; 86(10)60275028、60275820
86 (10) 60270825 China 1443 62
BeiJing Hwrk Chemicals Limted 4006990298;010-57411839;0757-86311057;021-51691807
010-87653215;0757-86311057;021-55236763 China 14833 55
Energy Chemical 021-58432009 / 400-005-6266
021-58436166-800 China 44192 61
Beijing Ouhe Technology Co., Ltd +86-10-4006331231;+86-10-51280831;+86-10-82967028
+86-10-82967029 China 10814 60
Shanghai Hanhong Scientific Co.,Ltd. 021-54302127,021-54306202,021-54308259,13764082696
+86-21-54291107 China 28712 64
Chengdu XiYa Chemical Technology Co., Ltd. 4008-626-111
028-84752058 China 9742 57

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