Calcium carbide | 75-20-7 (2023)


Calcium carbide (molecule formula: CaC2), is a kind of important chemical raw materials produced from the chemical processing of limestone. In 1892, H. Maysan (French) and H. Wilson (United state) simultaneously developed a calcium carbide production approach based on furnace Reduction. The United State had successfully achieved industrial production in 1895. The property of calcium carbide is related to its purity. Its industrial product is mostly the mixture of calcium carbide and calcium oxide, and also contains trace amounts of sulfur, phosphorus, nitrogen and other impurities. With the increasing content of impurities, it color exhibits gray, brown to black. The melting point and electrical conductivity both decrease with the decrease of the purity. The purity of its industrial product is usually 80% with m.p. being 1800~2000 °C. At room temperature, it does not react with air, but it can have oxidation reaction at above 350 ℃, and have reaction with nitrogen at 600~700 ℃ to generate calcium cyanamide. Calcium carbide, when coming across with water or steam, generates acetylene and release a large amount of heating. CaC2 + 2H2O─ → C2H2 + Ca (OH) 2 + 125185.32J, 1kg of pure calcium carbide can produce 366 L of acetylene 366l (15 ℃, 0.1MPa). Thereby, for its storage: calcium carbide should be strictly kept away from water. It is usually packed in a sealed iron container, and sometimes stored in a dry warehouse being filled with nitrogen if necessary.
Calcium carbide | 75-20-7 (1)





Chemical manufacture

Production of acetylene gas

(Video) Making Calcium Carbide in the Lab! - ElementalMaker

Raw materials,CaC2 + 2 H2O → C2H2 + Ca(OH)2

Production of various acetylene derivatives

Source of acetylene gas

Production of calcium hydroxide

Raw materials, CaC2 + 2 H2O → C2H2 + Ca(OH)2

Steel production

The desulfurisation of iron (pig iron, cast iron and steel)

Desulfurization agent

(Video) 5 Amazing Calcium Carbide Experiments

As a fuel in steelmaking

Extend the scrap ratio to liquid iron

Ladletreatment facilities

A powerful deoxidizer


Artificial ripening fruit

Source of acetylene gas


Signal flares

Floating, self-igniting naval signal flares

Used together with calcium phosphide

Cylinder gas

Metal fabrication and construction

Source of acetylene gas

Reaction with water

Calcium carbide will immediately have reaction upon coming across with water, generating acetylene and calcium hydroxide, which is the approach of industrial preparation of acetylene (carbide method), the reaction equation is:
CaC2 + 2H2O = C2H2 + Ca (OH) 2.
Since the impurity of calcium carbide, the generated acetylene gas is usually mixed with a small amount of hydrogen sulfide, phosphine gas and other contaminants, so there is a bad smell. Calcium carbide is produced from the lime and coke in an electric furnace at a high temperature of 3000 ℃:
3C + CaO = CaC2 + CO.
Upon the laboratory preparation of acetylene, owing to the reaction between calcium carbide and water is very fierce, we can apply saturated brine to substitute water so that a pure and smooth airflow of acetylene can be obtained. Calcium carbide won’t have reaction with sodium chloride.

Production method

Electric furnace reduction method is the only method for industrial production of calcium carbide at present. Put calcium oxide and coke for reduction reaction at 2000~2200 ℃: CaO + 3C─ → CaC2 + CO-480644.64J, the resulting molten calcium carbide flow into the receiver tank from the bottom of the reactor, and we obtain the final product after cooling. Calcium carbide production belongs to high temperature operation with relative large amount dust being produced and consuming a large amount of electrical energy. In 1980s, the production of per ton of calcium carbide consumes industrial power of about 10~11GJ. In order to reduce the power consumption, people mostly apply large-scale and closed calcium carbide furnace to reduce heat loss and also do good to the recycling of carbon monoxide.

(Video) Calcium Carbide & Acetylene - Periodic Table of Videos


Calcium carbide,is a binary salt. It is a grayish-black hard solid that reacts with water to produce acetylene gas, a solid corrosive that is calcium hydroxide, and release heat. Acetylene gas is manufactured by reacting calcium carbide with water. Because acetylene is so unstable, it is not shipped in bulk quantities.
Calcium carbide is shipped to acetylene-generating plants where it is reacted with water in a controlled reaction. After the reaction process, the acetylene gas is placed into specially designed containers with a honeycombed mesh inside for shipment and use. It is dissolved in acetone for stability. Calcium carbide has a specific gravity of 2.22, which is heavier than water. The four-digit UN identification number for calcium carbide is 1402. The NFPA 704 designation is health 3, flammability 3, and reactivity 2. The white section at the bottom of the diamond contains a W with a slash through it, indicating water reactivity. It is shipped in metal cans, drums, and specially designed covered bins on railcars and trucks. When shipped and stored, it should be kept in a cool, dry place. Primary uses are in the generation of acetylene gas for welding, vinyl acetate monomer, and as a reducing agent.

Chemical Properties

grey or black solid with a garlic-like odour

Physical properties

Grayish-black orthorhombic crystal; density 2.22 g/cm3; melts at 2,200°C; reacts with water.


Calcium carbide is used as a desulfurizer, dehydrant of steel, fuel in steel making, powerful deoxidizer and as a source of acetylene gas. It is used as a starting material for the preparation of calcium cyanamide, ethylene, chloroprene rubber, acetic acid, dicyandiamide and cyanide acetate. It is used in carbide lamps, toy cannons such as the big-bang cannon and bamboo cannon. It is associated with calcium phosphide and used in floating, self-igniting naval signal flares. Further, it is involved in the reduction of copper sulfide to metallic copper.


Calcium carbide (CaC2) has a garlic-like odor and reacts with water to form acetylene gasplus calcium hydroxide and heat. In the past, it was used in miners’ lamps to continuouslyproduce a small acetylene flame to provide some illumination in coal mines.


Calcium carbide is the most relevant carbide industrially because of its important role as the basis of acetylene industry. In locations where there is shortage of petroleum, Calcium Carbide is used as the starting material for the production of acetylene (1 kg of carbide yields ~300 liters acetylene), which, in turn, can be used as a building block for a range of organic chemicals (e.g. vinyl acetate, acetaldehyde and acetic acid). In some locations, acetylene is also used to produce vinyl chloride, the raw material for the production of PVC.
A less important use of Calcium Carbide is related to the ferilizers industry. It reacts with nitrogen to form calcium cyanamide, which is the starting material for the production of cyanamide (CH2N2). Cyanamide is a common agricultural product used to stimulate early foliation.
Calcium Carbide can also be employed as desulfurizing agent for producing low-sulfur carbon steel. Also, it is used as a reducing agent to produce metals from their salts, e.g., for direct reduction of copper sulfide to metallic copper.


Calcium carbide (CaC2) is manufactured by heating a lime and carbon mixture to 2000 to 2100°C (3632 to 3812°F) in an electric arc furnace. At those temperatures, the lime is reduced by carbon to calcium carbide and carbon monoxide (CO), according to the following reaction: CaO + 3C → CaC2 + CO
Lime for the reaction is usually made by calcining limestone in a kiln at the plant site. The sources of carbon for the reaction are petroleum coke, metallurgical coke, and anthracite coal. Because impurities in the furnace charge remain in the calcium carbide product, the lime should contain no more than 0.5 percent each of magnesium oxide, aluminum oxide, and iron oxide, and 0.004 percent phosphorus. Also, the coke charge should be low in ash and sulfur. Analyses indicate that 0.2 to 1.0 percent ash and 5 to 6 percent sulfur are typical in petroleum coke. About 991 kilograms (kg) (2,185 pounds [lb]) of lime, 683 kg (1,506 lb) of coke, and 17 to 20 kg (37 to 44 lb) of electrode paste are required to produce 1 megagram (Mg) (2,205 lb) of calcium carbide.


Calcium carbide is grayish-black solid, reacts with water yielding acetylene gas and calcium hydroxide, formed at electric furnace temperature from calcium oxide and carbon.

General Description

Grayish-black irregular lump solid. Used to make acetylene and in steel manufacture.

Air & Water Reactions

Reacts rapidly with water to generate the flammable gas acetylene and the base calcium hydroxide. Enough heat may be generated to ignite the gas [Jones, G.W. BM Report Invest. 3755 1944].

Reactivity Profile

Calcium carbide is a reducing agent. May react vigorously with oxidizing materials. The powdered mixture of the acetylide and iron oxide and iron chloride burns violently upon ignition, producing molten iron. Calcium carbide incandesces with chlorine, bromine, or iodine at 245, 350, or 305°C., respectively, [Mellor, 1946, Vol. 5, 862]. The carbide burns incandescently when mixed and heated with lead difluoride, magnesium, hydrogen chloride, and tin (II) chloride, [Mellor, 1946, 1940, 1946, and 1941], respectively. Interaction of Calcium carbide with methanol to give calcium methoxide is vigorous , but subject to an induction period of variable length. Once reaction starts, evolution of acetylene gas is very rapid, unpublished observations [Bretherick 1995]. Mixing Calcium carbide with silver nitrate solutions forms silver acetylide, a highly sensitive explosive. Copper salt solutions would behave similarly, [Photogr. Sci. Eng., 1966, 10, 334]. The mixture of Calcium carbide and sodium peroxide is explosive, as is Calcium carbide and perchloryl fluoride as gases at 100-300°C.


Forms flammable and explosive gas andcorrosive solid with moisture.

Health Hazard

It is a corrosive solid. Because it is highlywater-reactive, skin contact can cause burn.

Fire Hazard

Behavior in Fire: If wet by water, highly flammable acetylene gas is formed.

(Video) Calcium carbide is scary

Safety Profile

Reaction on contact with moisture forms explosive acetylene gas. Flammable on contact with moisture, acid or acid fumes; evolves heat or flammable vapors. Moderate explosion hazard. Incandescent reaction with Cl2 (245℃), Brz (350℃), IS (305℃), HCl gas + heat, PbF2, Mg + heat. Incompatible with Se, (KOH + Ch), AgNO3, Na2O2, SnCl2, S, water. Mixtures with iron(IⅡ) chloride, iron(IⅡ) oxide, tin(Ⅱ) chloride are easily ignited and burn fiercely. Vigorous reaction with methanol after an induction period. Addttion to silver nitrate solutions precipitates the dangerously explosive silver acetylide. Copper salt solutions behave similarly. See also CALCIUM HYDROXIDE and ACETYLENE.


What is calcium carbide used for? ›

Calcium Carbide is a grayish-black lump or crystalline (sand- like) powder with a garlic-like odor. It is used to generate Acetylene gas, as a reducing agent, and in steel manufacturing and metal cutting. Substance List because it is cited by DOT, NFPA and EPA.

Is calcium carbide illegal? ›

Consumption of fruits ripened with Calcium Carbide can cause severe health problems; therefore, the use of this Calcium Carbide for ripening is illegal in most countries.

Is calcium carbide harmful to health? ›

Calcium carbide treatment of food is extremely hazardous because it contains traces of arsenic and phosphorous. Once dissolved in water, the carbide produces acetylene gas. Acetylene gas may affect the neurological system by inducing prolonged hypoxia.

What happens when calcium carbide reacts with water? ›

The reaction of calcium carbide and water produces acetylene gas (C2H2) and calcium hydroxide.

Why shouldn't you touch calcium carbide with your own hands? ›

Hazard statement(s) H260 In contact with water releases flammable gases which may ignite spontaneously. H315 Causes skin irritation. H318 Causes serious eye damage. H335 May cause respiratory irritation.

Can we eat carbide? ›

The Food Safety and Standards Authority of India (FSSAI) has banned calcium carbide under the Prevention of Food Adulteration (PFA) Act, 1954. Anyone using it can be imprisoned for three years along with a fine of Rs 1,000.

Is carbide cancerous? ›

* There is limited evidence that Silicon Carbide causes cancer in animals. It may cause cancer of the lungs. * Many scientists believe there is no safe level of exposure to a carcinogen. Such substances may also have the potential for causing reproductive damage in humans.

What is the price of calcium carbide? ›

₹365.00 FREE Delivery.

Why should you not touch calcium metal? ›

Contact with skin will cause irritation and possible corrosion damage. Substance is severely irritating to the eyes and may injure eye tissue if not promptly removed. Acute and Chronic Effects: Calcium will react with water or moisture causing heat.

What is another name for calcium carbide? ›

Calcium carbide
Other names Calcium percarbide Calcium carbide Calcium dicarbide
CAS Number75-20-7
3D model (JSmol)Interactive image
37 more rows

Is it safe to eat artificially ripened bananas? ›

Calcium Carbide

Ripening using this process is not usually harmful. However, it is the traces of toxic arsenic and phosphorous left behind on fruits by this chemical that is harmful to human health.

Is calcium carbide flammable? ›

Chemical dangers

This produces highly flammable and explosive acetylene gas (ICSC 0089). This generates fire and explosion hazard. Reacts with chlorine, bromine, iodine, hydrogen chloride, lead, fluoride magnesium, sodium peroxide and sulfur. This generates fire and explosion hazard.

How do you neutralize calcium carbide? ›

Calcium carbide can be neutralized by adding various types of alcohol, such as ethanol, isopropanol, resulting in acetylene, vinyl ethers, calcium alkoxides and higher alcohols from decomposition of calcium alkoxides.

What happens when calcium carbide is treated with? ›

So when calcium carbide reacts with water it produces acetylene.

Is calcium carbide a hazardous waste? ›

This material is considered hazardous by the OSHA Hazard Communication Standard (29 CFR 1910.1200). Calcium Carbide, (75-20-7), 65-85%.

Why is calcium carbide sold in air tight metal cans? ›

(1) Packaging. (a) You must contain calcium carbide in metal packages of sufficient strength to prevent rupture. The packages must be provided with a screw top or equivalent. These packages must be constructed water- and air-tight.

Can you still get carbide? ›

Karst Sports is one of the few places you can buy carbide anymore.

How do you remove calcium carbide from fruit? ›

Dipping mangoes in 2% sodium carbonate solution for 12 hr can be used to remove arsenic residues from the calcium carbide ripened mangoes prior to their consumption.

How can you tell if a mango is ripe by calcium carbide? ›

Mango fruit starts to get black patches in 2 to 3 days due to the usage of calcium carbide for ripening of Mango fruit. Traces of white color powder arsenic traces are found on the mango fruit; if Calcium Carbide is applied, there will be traces of arsenic powder white powder.

How do you know if a banana is carbide? ›

How to Identify Carbide Ripe Bananas- Actually, naturally ripe bananas have light brown and black spots and they are sweet to eat. Their skin is dark yellow and stained. At the same time, the forts cooked with carbide or chemical etc. are very plain and light yellow in color.

What are the side effects of carbide? ›

According to studies, calcium carbide can also affect the neurological system by inducing prolonged hypoxia. It causes symptoms like headache, dizziness, high sleepiness, memory loss, cerebral oedema, numbness in the legs and hands, general weakness, cold and damp skin, low blood pressure and seizure.

Which is better titanium or carbide? ›

Scratch-resistance - Due to its hardness tungsten carbide handily beats titanium when it comes to scratch-resistance, though titanium is still considerably more scratch-resistant than other popular materials. There are virtually no materials other than a diamond that can scratch tungsten carbide.

Is diamond better than carbide? ›

Superabrasive, diamond plated tools have a major edge over carbide—longevity and cut-rate set diamond tools apart from the rest. Initially, a diamond tool will cost more money, but this investment goes toward the extended life of the bit. Additionally, diamond tools have a closer cut tolerance than carbide does.

Where do you get calcium carbide from? ›

Calcium carbide is synthesized industrially from calcium oxide (lime), CaO, and carbon in the form of coke at about 2,200 °C (4,000 °F).

Is calcium carbide edible? ›

Potential Health Effects associated with Calcium Carbide

Calcium Carbide is a dangerous and corrosive chemical. Carbide ripened fruits on consumption cause several harmful effects to human health. As discussed earlier, CaC2 has cancer causing properties and contains traces of arsenic and phosphorous hydride.

Is carbide harder than steel? ›

Carbide is much harder than steel and much more resistant to heat. Although a carbide-tipped tool is more expensive than a comparable tool which has steel cutting edges, carbide is more economical because it lasts much longer.

How strong is carbide? ›

The Mohs' hardness of tungsten carbide is “9.” It boasts a level of hardness second to diamond.

How do you identify calcium carbide? ›

The procedure is very simple and cost effective. Wash the test fruit with 10ml of water and take 1ml of the wash and mix with equal volume of sensor solution in a glass test tube and mix. The change in colour of solution from red to purple indicates that calcium carbide is used for ripening the fruit.

What is the source of carbide? ›

Carbides are prepared from carbon and an element of similar or lower electronegativity, usually either a metal or a metal oxide, at temperatures of 1,000–2,800 °C (1,800–5,100 °F). Almost any carbide can be prepared by one of several general methods.

What happens when you put calcium metal in water? ›

Calcium metal is an alkaline earth metal found in Group 2A and reacts with water to form calcium hydroxide and hydrogen gas.

Can you cut calcium with a knife? ›

Calcium is an alkaline earth metal. It can also be easily cut with a knife. Magnesium is a bit hard as it has a small size and 2 electrons in the valence shell.

Is calcium metal explosive? ›

Calcium can react violently with WATER, STEAM, MOISTURE and STRONG ACIDS (such as HYDROCHLORIC, SULFURIC and NITRIC) to form flammable and explosive Hydrogen gas. Finely divided Calcium can ignite in AIR or in the presence of HALOGENS (such as CHLORINE and FLUORINE).

Is calcium carbide used in welding? ›

It is used as a raw material for the production of several organic chemicals, as well as a fuel component in metal cutting, and oxy-acetylene welding.

Can we use calcium carbide as fuel? ›

Calcium carbide, which produces acetylene gas upon reaction with water, could possibly be used as a vehicle fuel, although handling acetylene presents serious problems. Aluminum carbide produces methane, a more controllable gas, but has the disadvantage of releasing substantial heat during hydrolysis.

Is calcium carbide found in nature? ›

The main use for this substance is in the production of the flammable gas acetylene. It is necessary to produce calcium carbide industrially, because it is not naturally occurring in large amounts.

Which fruits Cannot be artificially ripened? ›

Non-climacteric fruits: these fruits do not ripen after harvest. So in order to attain full ripeness and flavour, these fruits are often harvested once they have fully matured and ripened in the orchard. These include fruits like lemons, oranges, grape, cherry, pineapple, and strawberry.

Are apples artificially ripened? ›

Therefore, the consumption of fruit is high but fruits like papaya, banana, apple and others are sold after using crude chemical calcium carbide (CaC2) popularly known as 'masala' for artificially ripening them.

Why are bananas seedless now? ›

Put simply, bananas don't have seeds because they don't need them. Because all bananas have been propagated vegetatively (as this process is called), all bananas are sterile clones, and just about all of the bananas you find in the grocery store are a single breed, Cavendish.

What is the shelf life of calcium carbide? ›

The shelf-life observed for 2 g calcium carbide treated banana was 3.5 days in batch A and 3 days in batch B.

Does vinegar remove calcium? ›

White vinegar, baking soda and even a lemon can be used to get rid of pesky calcium stains. Many homemakers already use vinegar to help clean difficult areas. It's also helpful when addressing hard water stains or calcium buildup. Use a spray bottle or cloth damp with vinegar to wet the area.

What is the main use of calcium carbide? ›

Calcium carbide has three main uses: the manufacture of acetylene, ... reaction with nitrogen to give cyanamide ... and the desulfurization of hot metal, cast iron, and steel.

What happens when calcium carbide is heated? ›

Calcium carbide reacts vigorously with even mere traces of Н₂O, releasing a large amount of heat. If there is an insufficient quantity of water, the resulting acetylide spontaneously combusts.

Is calcium carbide a fertilizer? ›

Calcium Carbonate in the agricultural industry

Limestone is a source of calcium carbonate and is used as a fertilizer for agricultural soils, since it increases the pH of acidic soils. This increase in PH increases soil fertility and makes plants better assimilate nitrogen, phosphorus and potassium.

Can carbide be purchased? ›

Karst Sports is one of the few places you can buy carbide anymore. The shipment is actually handled by HQ, but the price is cheaper from Karst Sports than it is at HQ.

Is calcium carbide renewable? ›

Calcium carbide (CaC2) is a renewable chemical, which can be recycled from calcium that is abundant in the Earth's crust.

Can carbide be welded to steel? ›

Brazing is a reliable method of joining carbides to steel shanks and other base materials. However, you must consider the difference in CTE between the carbide and the base material. During heating and cooling, the base material will typically expand and contract at a higher rate than the carbide.

Which carbide is most hard? ›

Tungsten carbide is often known as a hard metal owing to its high hardness compared to other ceramic powders. Tungsten carbide has a high melting point of 2870°C.

How do you apply calcium carbide to plants? ›

To apply, mix three or four calcium carbide pellets into a cup of ice water. When it stops fizzing, pour the mixture into the center of the rosette whorl in the middle of the leaves atop the plant. If there is dew sitting in the whorl already, you may choose to drop the calcium carbide directly into the dew.

Is calcium carbide good for plants? ›

Calcium carbide being source of acetylene and ethylene can promote plant growth and yield of crops more than other sources (Muromtsev et al., 1991;Mahmood et al., 2009;Siddiq et al., 2012).

Why do farmers add calcium oxide to soil? ›

The addition of calcium oxide or calcium-magnesium oxide enables the acidity of soil to be to neutralised by adjusting pH, which helps to: Prepare the soil for the crop to absorb the nutrients in excellent conditions.


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