Receipt
In the laboratory
In the laboratory, as well as in gas welding equipment, acetylene is obtained by the action of water on calcium carbide (F. Wöhler, 1862),
The resulting acetylene has a high degree of purity of 99.9%. The main disadvantage of the process is the high power consumption: 10,000-11,000 kWh per 1 ton of acetylene.
Physical properties
Acetylene requires great care in handling. May explode on impact, when heated to 500 °C or when compressed above 0.2 MPa at room temperature. A jet of acetylene released into the open air can ignite from the slightest spark, including from the discharge of static electricity from a finger. Acetylene is stored in special cylinders filled with a porous material impregnated with acetone.
Chemical properties
Acetylene (ethyne) is characterized by addition reactions:
HC≡CH + Cl 2 -> ClCH=CHCl
Acetylene with water, in the presence of salts and other catalysts, forms acetaldehyde (Kucherov's reaction). Due to the presence of a triple bond, the molecule is high-energy and has a high specific heat of combustion - 14,000 kcal/m³ (50.4 MJ/kg). When burned in oxygen, the flame temperature reaches 3150 °C. Acetylene can polymerize to benzene and other organic compounds (polyacetylene, vinylacetylene). Polymerization to benzene requires graphite and a temperature of ~500 °C. In the presence of catalysts such as nickel tricarbonyl(triphenylphosphine) the temperature of the cyclization reaction can be lowered to 60-70°C.
The main chemical reactions of acetylene (addition reactions, summary table 1.):
The main chemical reactions of acetylene (reactions of addition, dimerization, polymerization, cyclomerization, summary table 2.):
It reacts with ammonia solutions of Cu(I) and Ag(I) salts to form sparingly soluble, explosive acetylenides - this reaction is used for the qualitative determination of acetylene and its distinction from alkenes (which also decolorize bromine water and potassium permanganate solution).
Story
Application
Acetylene is used:
Security
Since acetylene is insoluble in water and its mixtures with oxygen can explode over a very wide range of concentrations, it cannot be collected in gas meters.
Acetylene explodes at a temperature of about 500 ° C or a pressure above 0.2 MPa; CPV 2.3-80.7%, self-ignition temperature 335 °C. The explosiveness is reduced when acetylene is diluted with other gases, such as nitrogen, methane, or propane.
With prolonged contact of acetylene with copper and silver, copper and silver acetylenides are formed, which explode on impact or an increase in temperature. Therefore, when storing acetylene, materials containing copper (for example, cylinder valves) are not used.
Acetylene has a slight toxic effect. For acetylene, MPCm.r. is normalized. = MPC s.s. = 1.5 mg/m³ according to hygienic standards GN 2.1.6.1338-03 "Maximum Permissible Concentrations (MPC) of pollutants in the atmospheric air of populated areas".
MPKr.z. (working area) is not installed (according to GOST 5457-75 and GN 2.2.5.1314-03), since the concentration limits of flame distribution in a mixture with air is 2.5-100%.
It is stored and transported in white steel cylinders filled with an inert porous mass (for example, charcoal) (with a red inscription "A") in the form of a solution in acetone under a pressure of 1.5-2.5 MPa.
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Notes
Literature
- Miller S. A. Acetylene, its properties, production and application. - L.: Chemistry, 1969. - T. 1. - 680 p.
- Korolchenko A. Ya., Korolchenko D. A. Fire and explosion hazard of substances and materials and means of extinguishing them. Handbook: in 2 parts. Part 1. - M .: Pozhnauka Association, 2004. - 713 p. - ISBN 5-901283-02-3.
Links
- // Encyclopedic Dictionary of Brockhaus and Efron: in 86 volumes (82 volumes and 4 additional). - St. Petersburg. , 1890-1907.
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An excerpt characterizing Acetylene
- You better wait until you get married ...- You know, - said Anatole, - j "adore les petites filles: [I love girls:] - now he will be lost.
- You already got caught once on a petite fille [girl], - said Dolokhov, who knew about Anatole's marriage. - Look!
Well, you can't do it twice! BUT? - said Anatole, laughing good-naturedly.
The next day after the theater, the Rostovs did not go anywhere and no one came to them. Marya Dmitrievna, hiding from Natasha, was talking to her father about something. Natasha guessed that they were talking about the old prince and inventing something, and she was worried and offended by this. She waited every minute for Prince Andrei, and twice that day sent the janitor to Vzdvizhenka to find out if he had arrived. He didn't come. It was now harder for her than the first days of her arrival. Her impatience and sadness for him were joined by an unpleasant recollection of a meeting with Princess Marya and the old prince, and fear and anxiety, for which she did not know the reason. It seemed to her that either he would never come, or that before he arrived, something would happen to her. She could not, as before, calmly and for a long time, alone with herself, think about him. As soon as she began to think about him, the recollection of him was joined by the recollection of the old prince, of Princess Mary, and of the last performance, and of Kuragin. She again presented herself with the question of whether she was to blame, whether her loyalty to Prince Andrei had already been violated, and again she found herself remembering every word, every gesture, every shade of the play of expression on the face of this man, who knew how to arouse in her incomprehensible for her and a terrible feeling. In the eyes of her family, Natasha seemed livelier than usual, but she was far from being as calm and happy as she had been before.
On Sunday morning, Marya Dmitrievna invited her guests to Mass at her parish of the Assumption on Mogiltsy.
“I don’t like these fashionable churches,” she said, apparently proud of her free-thinking. “There is only one God everywhere. Our priest is fine, he serves decently, it's so noble, and so is the deacon. Is it any holiness from this that they sing concerts on the kliros? I do not like, one pampering!
Marya Dmitrievna loved Sundays and knew how to celebrate them. Her house was all washed and cleaned on Saturday; people and she did not work, everyone was festively discharged, and everyone was at mass. Meals were added to the master's dinner, and people were given vodka and a roasted goose or pig. But on nothing in the whole house was the holiday so noticeable as on the broad, stern face of Marya Dmitrievna, which on that day assumed an unchanging expression of solemnity.
When they had drunk coffee after mass, in the living room with the covers removed, Marya Dmitrievna was informed that the carriage was ready, and with a stern look, dressed in a ceremonial shawl in which she made visits, she got up and announced that she was going to Prince Nikolai Andreevich Bolkonsky to explain to him about Natasha.
After the departure of Marya Dmitrievna, a fashionista from Madame Chalmet came to the Rostovs, and Natasha, having closed the door in the room next to the living room, very pleased with the entertainment, began trying on new dresses. While she, putting on a bodice that was still sleeveless, swept on a living thread, and bending her head, looked in the mirror at how her back was sitting, she heard in the living room the lively sounds of her father's voice and another, female voice, which made her blush. It was Ellen's voice. Before Natasha had time to take off the bodice she was trying on, the door opened and Countess Bezukhaya entered the room, beaming with a good-natured and affectionate smile, in a dark purple, high-necked velvet dress.
Ah, ma delicieuse! [Oh, my lovely!] - she said to the blushing Natasha. - Charmante! [Charming!] No, it's not like anything, my dear count, - she said to Ilya Andreevich, who came in after her. - How to live in Moscow and not go anywhere? No, I won't leave you! This evening m lle Georges is declaiming at my place and some people will gather; and if you don't bring your beauties, who are better than m lle Georges, then I don't want to know you. There is no husband, he went to Tver, otherwise I would have sent him for you. By all means come, by all means, at the ninth hour. She nodded her head at the familiar fashionista, who respectfully crouched down to her, and sat down on an armchair near the mirror, picturesquely spreading the folds of her velvet dress. She did not stop chatting good-naturedly and cheerfully, constantly admiring Natasha's beauty. She examined her dresses and praised them, and also boasted of her new dress en gaz metallique [made of metal-colored gauze] which she had received from Paris and advised Natasha to do the same.
“However, everything suits you, my lovely,” she said.
A smile of pleasure never left Natasha's face. She felt happy and flourishing under the praises of this dear Countess Bezukhova, who had previously seemed to her such an impregnable and important lady, and who was now so kind to her. Natasha became cheerful and felt almost in love with this beautiful and such good-natured woman. Helen, for her part, sincerely admired Natasha and wanted to amuse her. Anatole asked her to set him up with Natasha, and for this she came to the Rostovs. The thought of bringing her brother together with Natasha amused her.
In spite of the fact that she had previously been annoyed with Natasha for having wrested Boris from her in Petersburg, now she did not even think about it, and with all her heart, in her own way, wished Natasha well. Leaving the Rostovs, she withdrew her protegee aside.
- Yesterday my brother dined with me - we were dying of laughter - he does not eat anything and sighs for you, my charm. Il est fou, mais fou amoureux de vous, ma chere. [He's crazy, but he's crazy in love with you, my dear.]
Natasha blushed purple upon hearing these words.
- How blushing, how blushing, ma delicieuse! [my charm!] - Helen said. - You should definitely come. Si vous aimez quelqu "un, ma delicieuse, ce n" est pas une raison pour se cloitrer. Si meme vous etes promise, je suis sure que votre promis aurait desire que vous alliez dans le monde en son absence plutot que deperir d "ennui. [From the fact that you love someone, my lovely, you should not live as a nun. Even if you're a bride, I'm sure your fiancé would rather have you go out into the world in his absence than die of boredom.]
“So she knows that I am a bride, so she and her husband, with Pierre, with this fair Pierre, Natasha thought, talked and laughed about it. So it was nothing." And again, under the influence of Helen, what had previously seemed terrible seemed simple and natural. “And she is such a grande dame, [important lady,] so sweet and so evidently loves me with all her heart,” thought Natasha. And why not have fun? thought Natasha, looking at Helen with surprised, wide-open eyes.
Marya Dmitrievna returned to dinner, silent and serious, obviously having suffered a defeat at the old prince's. She was still too excited about the collision to be able to calmly tell the story. To the question of the count, she answered that everything was fine and that she would tell tomorrow. Learning about the visit of Countess Bezukhova and the invitation to the evening, Marya Dmitrievna said:
- I don’t like to hang out with Bezukhova and I won’t advise; Well, yes, if you promised, go, you’ll be scattered, ”she added, turning to Natasha.
Count Ilya Andreich took his girls to Countess Bezukhova. There were quite a lot of people at the evening. But the whole society was almost unfamiliar to Natasha. Count Ilya Andreevich noted with displeasure that all this society consisted mainly of men and women, known for their liberties of treatment. M lle Georges, surrounded by young people, stood in the corner of the living room. There were several Frenchmen, among them Metivier, who, since Helene's arrival, had been her housewife. Count Ilya Andreich made up his mind not to sit down at cards, not to leave his daughters, and to leave as soon as the performance of Georges was over.
Anatole was apparently at the door waiting for the Rostovs to enter. He immediately greeted the count, went up to Natasha and followed her. As soon as Natasha saw him, just as in the theater, a feeling of conceited pleasure that he liked her and fear from the absence of moral barriers between her and him seized her. Helen joyfully received Natasha and loudly admired her beauty and toilet. Shortly after their arrival, m lle Georges left the room to dress. In the living room they began to arrange chairs and sit down. Anatole moved a chair to Natasha and wanted to sit beside her, but the count, who did not take his eyes off Natasha, sat down beside her. Anatole sat in the back.
M lle Georges, with bare, dimpled, thick arms, in a red shawl worn over one shoulder, stepped into the empty space left for her between the chairs and stopped in an unnatural pose. An enthusiastic whisper was heard. M lle Georges looked sternly and gloomily at the audience and began to speak some verses in French, which dealt with her criminal love for her son. In places she raised her voice, in places she whispered, solemnly raising her head, in places she stopped and wheezed, rolling her eyes.
- Adorable, divin, delicieux! [Amazing, divine, wonderful!] - was heard from all sides. Natasha looked at fat Georges, but heard nothing, saw nothing, and understood nothing of what was going on in front of her; she only felt completely irrevocable again in that strange, insane world, so far from the former, in that world in which it was impossible to know what was good, what was bad, what was reasonable and what was insane. Behind her sat Anatole, and she, feeling his closeness, fearfully waited for something.
After the first monologue, the whole society stood up and surrounded m lle Georges, expressing their delight to her.
- How good she is! Natasha said to her father, who, along with the others, got up and moved towards the actress through the crowd.
“I can’t find it, looking at you,” Anatole said, following Natasha. He said it at a time when she alone could hear him. - You are charming ... from the moment I saw you, I did not stop ....
“Let’s go, let’s go, Natasha,” said the count, returning for his daughter. - How good!
Natasha, without saying anything, went up to her father and looked at him with questioning surprised eyes.
After several receptions of recitation, m lle Georges left and the Countess Bezuhaya asked for company in the hall.
The count wanted to leave, but Helen begged not to spoil her impromptu ball. The Rostovs remained. Anatole invited Natasha to a waltz, and during the waltz, he, shaking her waist and hand, told her that she was ravissante [charming] and that he loved her. During the ecossaise, which she again danced with Kuragin, when they were alone, Anatole did not say anything to her and only looked at her. Natasha was in doubt if she saw in a dream what he said to her during the waltz. At the end of the first figure, he again shook hands with her. Natasha looked up at him with frightened eyes, but such a self-confidently tender expression was in his affectionate look and smile that she could not, looking at him, say what she had to tell him. She lowered her eyes.
“Don't tell me such things, I'm engaged and in love with another,” she said quickly ... - She looked at him. Anatole was not embarrassed or upset by what she said.
- Don't tell me about it. What is my business? - he said. “I'm saying I'm madly, madly in love with you. Is it my fault that you are amazing? We start.
Alkynes (otherwise acetylenic hydrocarbons) are hydrocarbons containing a triple bond between carbon atoms, with the general formula CnH2n-2. The carbon atoms in the triple bond are in a state of sp - hybridization.
Reaction of acetylene with bromine water
The acetylene molecule contains a triple bond, bromine destroys it and joins the acetylene. Terabromomethane is formed. Bromine is consumed in the formation of tetrabromoethane. Bromine water (yellow) - discolors.
This reaction proceeds at a lower rate than in the series of ethylene hydrocarbons. The reaction also proceeds in steps:
HC ≡ CH + Br 2 → CHBr = CHBr + Br 2 → CHBr 2 - CHBr 2
acetylene → 1,2-dibromoethane → 1,1,2,2-tetrabromoethane
The decolorization of bromine water proves the unsaturation of acetylene.
The reaction of acetylene with a solution of potassium permanganate
In a solution of potassium permanganate, acetylene is oxidized, and the molecule breaks at the site of the triple bond, the solution quickly becomes colorless.
3HC ≡ CH + 10KMnO 4 + 2H 2 O → 6CO 2 + 10KOH + 10MnO 2
This reaction is a qualitative reaction for double and triple bonds.
The reaction of acetylene with an ammonia solution of silver oxide
If acetylene is passed through an ammonia solution of silver oxide, the hydrogen atoms in the acetylene molecule are easily replaced by metals, since they have high mobility. In this experiment, hydrogen atoms are replaced by silver atoms. Silver acetylenide is formed - a yellow precipitate (explosive).
CH ≡ CH + OH → AgC≡CAg↓ + NH 3 + H 2 O
This reaction is a qualitative reaction for a triple bond.
Theme classes on KTP No. 37 Alkina. Acetylene its structure and properties
Target Form the concept of unsaturated hydrocarbons (alkynes). To introduce students to the structure and properties of alkynes using the example of acetylene
To systematize and generalize the knowledge about the marginal hydrocarbons and give a comparative description of alkanes, alkenes and alkynes.
Acetylene and its homologues
Hydrocarbons with the general formula CnH2n-2, in whose molecules there is one triple bond, belong to the acetylene series. According to the international nomenclature, hydrocarbons of the acetylene series are called alkynes. Like hydrocarbons of the ethylene series, the formulas of the hydrocarbons of the acetylene series can be derived from the formulas of saturated hydrocarbons. Their names are formed by replacing the suffix -AN with -IN.
The simplest homologues of acetylene
Physical properties
Acetylene is a gas lighter than air, slightly soluble in water, almost odorless in its pure form. Changes in the physical properties of hydrocarbons of the acetylene series (as well as for alkanes and alkenes) obey the general laws: with an increase in the relative molecular weight, the boiling point of substances increases.
Chemical properties
Acetylene and its homologues are characterized by addition, oxidation and polymerization reactions.
1. Addition reactions
Hydrocarbons of the acetylene series react with halogens. For example, acetylene decolorizes bromine water. The addition of bromine occurs in two stages:
At elevated temperatures, acetylene adds hydrogen. Hydrogenation of acetylene also occurs in two stages:
Acetylene also reacts with complex substances. For example, in the presence of mercury (II) sulfate, acetylene adds water, and acetaldehyde (acetic aldehyde) is formed:
If hydrogen chloride is added to acetylene, then a gaseous substance vinyl chloride, or vinyl chloride, is formed:
Vinyl chloride is able to polymerize:
2.Oxidation reactions
Acetylene decolorizes potassium permanganate solution.
In air, acetylene burns with a smoky flame.
3. Polymerization reactions
Acetylene can polymerize to benzene:
Receipt
In the laboratory and in industry, acetylene is obtained by reacting calcium carbide with water:
Application
1 For cutting and welding metals;
2 to obtain artificial fibers,
3 dyes,
4 varnishes,
5 perfumes and colognes,
6 drugs,
7 chloroprene rubber,
8 PVC
Questions for self-control
Liquid
Acetylene- unsaturated hydrocarbon C 2 H 2. It has a triple bond between carbon atoms, belongs to the class of alkynes.
Physical properties
Under normal conditions, it is a colorless gas, sparingly soluble in water, lighter than air. Boiling point -83.8 °C. When compressed, it decomposes with an explosion, stored in cylinders filled with diatomaceous earth or activated carbon impregnated with acetone, in which acetylene dissolves under pressure in large quantities. Explosive. Cannot be released into the open air. Particles C 2 H 2 are on Uranus and Neptune.
Chemical properties
Acetylene-oxygen flame (core temperature 3300 °C)
Acetylene (ethyne) is characterized by addition reactions:
HC≡CH + Cl 2 -> СlCH=CHCl
Acetylene with water, in the presence of mercury salts and other catalysts, forms acetaldehyde (Kucherov's reaction). Due to the presence of a triple bond, the molecule is high-energy and has a high specific heat of combustion - 14,000 kcal/m³. During combustion, the flame temperature reaches 3300°C. Acetylene can polymerize to benzene and other organic compounds (polyacetylene, vinylacetylene). Polymerization to benzene requires graphite and a temperature of 400 °C.
In addition, the hydrogen atoms of acetylene are relatively easy to split off in the form of protons, that is, it exhibits acidic properties. So acetylene displaces methaniz of an ether solution of methylmagnesium bromide (a solution containing acetylenide ion is formed), forms insoluble explosive precipitates with silver salts and monovalent copper.
Acetylene decolorizes bromine water and potassium permanganate solution.
The main chemical reactions of acetylene (addition reactions, summary table 1.):
Story
Opened in 1836 by E. Davy, synthesized from coal and hydrogen (arc discharge between two carbon electrodes in a hydrogen atmosphere) by M. Berthelot (1862).
Mode of production
In industry, acetylene is often obtained by the action of water on calcium carbide, see the video of this process (F. Wöhler, 1862), as well as by the dehydrogenation of two methane molecules at temperatures above 1400 ° Celsius.
Application
Acetylene lamp
Acetylene is used:
- for welding and cutting metals,
- as a source of very bright, white light in self-contained fixtures, where it is obtained by the reaction of calcium carbide and water (see carbide),
- in the production of explosives (see acetylides),
- for the production of acetic acid, ethyl alcohol, solvents, plastics, rubber, aromatic hydrocarbons.
Security
Since acetylene is soluble in water and mixtures with oxygen can explode over a very wide range of concentrations, it cannot be collected in gas meters. Acetylene explodes at a temperature of about 500 ° C or a pressure above 0.2 MPa; CPV 2.3-80.7%, self-ignition temperature 335 °C. Explosiveness is reduced by diluting acetylene with other gases, such as N 2 , methane or propane. With prolonged contact of acetylene with copper or silver, explosive acetylene copper or acetylene silver is formed, which explode on impact or an increase in temperature. Therefore, when storing acetylene, materials containing copper (for example, cylinder valves) are not used. Acetylene has a weak toxic effect. For acetylene, MPCm.r. is normalized. = MPC s.s. = 1.5 mg/m3 according to hygienic standards GN 2.1.6.1338-03 "Maximum Permissible Concentrations (MPC) of Pollutants in the Atmospheric Air of Populated Areas". MPKr.z. (working area) is not installed (according to GOST 5457-75 and GN 2.2.5.1314-03), because the concentration limits of the distribution of the flame in a mixture with air is 2.5-100%. It is stored and transported in white steel cylinders filled with an inert porous mass (for example, charcoal) (with a red inscription "A") in the form of a solution in acetone under a pressure of 1.5-2.5 MPa.
Acetylene is a chemical substance, hydrocarbon, the simplest alkyne, having the chemical formula C2H2 (C 2 H 2), with a boiling point of -84°C, and a molar mass of 26.04 g/mol. Under atmospheric conditions, acetylene is a colorless gas with a density at +20°C and an absolute pressure of 1 bar 1.097 kg/m³ (lighter than air), a density at 0°C 1.1716 kg/m³, odorless (the well-known smell of garlic is present in used in industry and non-industrial non-laboratory applications of acetylene due to impurities of phosphorus and hydrogen sulfide). Acetylene gas is slightly soluble in water, but easily soluble in acetone and ethyl alcohol.
Reactions of acetylene
Acetylene burns at a concentration in air from 2.5% to 80% (and almost up to 100% under certain conditions; at a concentration of 100% and the coincidence of certain conditions, acetylene can violently, with an explosion, self-decompose into carbon and hydrogen), with the formation of very hot, bright and smoky flames. The combustion temperature of acetylene in air or oxygen can reach 3300°C.
In reactions with metals such as copper, silver and mercury, as well as their alloys and salts, acetylene forms acetylenides. For example, silver nitrate reacts with acetylene to form silver acetylenide and nitric acid:
2AgNO 3 + C2H2 → Ag 2 C 2 + 2HNO 3
Some acetylenides, including the aforementioned silver acetylenide Ag2C2, are strong and dangerous explosives to handle, detonating on heating and also on impact. Cases are known when silver acetylenide was formed at the joints of pipes for transporting acetylene, which were soldered with silver solder.
The German chemist Walter Reppe discovered that, in the presence of metal catalysts, acetylene can react with many substances to form industrially significant chemical compounds. These reactions are now called by his name, the Reppe reactions.
Reactions of C2H2 acetylene with ROH alcohols, hydrocyanic acid HCN, hydrochloric acid HCl, or carboxylic acids give vinyl compounds. For example, acetylene and hydrochloric acid:
C2H2 + HCl →
The reaction of ethylene with carbon monoxide gives acrylic acid or acrylic esters used in the manufacture of organic glass:
C2H2 + CO + H2O → CH 2 \u003d CHCO 2 H
The cyclization reaction allows you to convert acetylene to benzene:
3C2H2 → C6H6
Getting acetylene
Basically, acetylene is produced by incomplete combustion of methane or as a by-product and unwanted product in the production of ethylene by hydrocarbon cracking (part of this unwanted acetylene is catalytically hydrogenated to ethylene). The annual production of acetylene by the latter method is approximately 400,000 tons.
Until the 1950s, when oil replaced coal as a source of carbon, acetylene was one of the main raw materials in the chemical industry. Then (and still in laboratory conditions) acetylene was produced by hydrolysis of calcium carbide:
CaC2 + 2H 2 O → Ca(OH) 2 + C2H2
Acetylene cylinders
Acetylene can be liquefied and solidified, however, both in the gaseous state at pressures above about 7 bar, and in the liquid and solid state, acetylene is shock-sensitive and explosive. Therefore, acetylene is always supplied to users in cylinders dissolved in acetone or dimethylformamide and completely filled with Agamassan (or AGA-massan, which stands for “AGA compound” in Swedish). AGA is the name of a Swedish manufacturer and supplier of industrial gases , now a division of Linde Gas, founded at one time by the inventor of Agamassan "a Gustaf Dalen. Agamassan" includes asbestos, cement, coal and diatomaceous earth). As an alternative to Agamassan, a diatomaceous earth or ceramic/silicate lime filler can be used.
In acetylene cylinders, it is usually not more than 17 bar, and the outlet pressure from the cylinder is not more than 1 bar, and usually about 0.5 bar.
Acetylene cylinders are usually equipped with both conventional pressure relief valves, including passing and isothermal pressure relief valves, and special safety valves, which operate when the temperature rises above 100°C, releasing acetylene into the atmosphere. These valves act like fusible links.
In Russia, acetylene cylinders are painted white, with "Acetylene" written in red.
Use of acetylene
The most well-known area of acetylene use is oxy-acetylene welding. Oxy-acetylene cutting of metals is also widespread. Both uses are due to the extremely high combustion temperature of acetylene. Approximately 20% of the industrially produced acetylene in the world is used for these purposes. However, the use of acetylene welding is gradually declining due to the growing popularity of electric arc welding - cutting with acetylene with oxygen, however, remains as common.
In the chemical industry, acetylene is used in the synthesis of many organic compounds such as acetaldehyde and acetic acid.
Among obsolete applications is the use of acetylene as a light source (the so-called carbide lamps, in which calcium carbide CaC2 released acetylene when it reacted with water, and the acetylene was burned, were used, for example, as headlights in all the first cars).
Acetylene has been used in the past as a general anesthetic. At the same time, it can be noted that when handling acetylene, one should usually not be particularly afraid of its physiological effects: before the concentration of acetylene in the inhaled air reaches dangerous limits, the lower flammability threshold will be exceeded long ago (recall, this is 2.5%) - that poses a much greater risk.
