[Chemistry Class Notes] on Acetylene Pdf for Exam

Acetylene can also be referred to as Ethyne also known as Narcylen as well as Vinylene. It is used extensively as chemical building blocks and as fuel. It is, in its basic form, unstable and is used as it is a solution. The compound is unsaturated and. The two carbon atoms that make it are connected by two bonds.

Vinylene is a non-colourless gas that has a slight scent reminiscent of ether. It readily dissolves in chloroform, water, acetone and benzene. It is somewhat solubilized in carbon disulfide as well as alcohol. It is lighter compared to air and is able to ignite. Prolonged exposure to flame or heat could cause the containers to crack quickly.

Principal Uses

Illuminant, oxyacetylene welding cutting and soldering of metals; signaling; precipitating copper, in particular, and acetaldehyde; production of Acetic acid.

It is used for brazing metalizing as well as hardening, flame scaring as well as local heating in metallurgical processes. Flames are also employed in glass manufacturing. Chemically, acetylene can be used in the production of artificial rubber  butyrolactone Vinyl alkyl ether and pyrrolidone.It is employed to braze as well as local heating and in the glass industry.

In the chemical industry, acetylene can be used as a feedstock in the manufacture of acrylonitrile, vinyl chloride the synthetic rubber, vinyl acetate butyrolactone, acrylate, trichloroethylene 1,4-butanediol and vinyl alkyl ethers and pyrrolidone and so on.

It is employed for cutting, welding metalizing, brazing, making damaged materials, surface hardening, locally hardening and securing, scarifying localized heating (shrink fitting, etc.).

Fabrication of vinyl chloride vinyl acetate, acrylates, acrylonitrile Acetaldehyde; per- and trichloroethylene 1,4-butanediol, cyclooctatetraene black; as well as cutting and welding of metals.

Chem Int. for Acrylic Acid chlorinated solvents and tetrahydrofuran and other chemical compounds.

Products made from acetylene include vinyl chloride monomer, acetylene black, vinyl fluoride, N-vinyl carbazole, N-vinyl caprolactam and other derivatives such as 1,4-butanediol, vinyl ethers, N-vinyl-2-pyrrolidone, and vinyl esters.

Acetylene was employed during the 1900s to serve as an anesthetic (under the name Marceline). It is not used anymore as an anesthetic due to more effective alternatives that are less explosive are now available.

A key industrial material of raw materials, Acetylene can be utilized to make alkenes and solvents, which are then used as monomers in the production of plastic. It is also employed in cutting, brazing, flame scarfing, the metallurgical heating and hardening process, as well as in the industry of glass. In optometry, it is an ingredient in contact lenses. As with ethylene, acetylene can be used to mature fruit and mature trees, flowers.

In the black process of acetylene, the acetylene and the air are ignited to warm the vessel in which it is being used. It is shut off, allowing Acetylene to break down into hydrogen and carbon in lack of oxygen. This leads to … one of the “purest” carbon blacks.

Other Details

Acetylene is an emitted gas (C₂H₂) made up of hydrogen and carbon. Acetylene is known as D.A.– Dissolved Acetylene. The cylinder has a maroon color. oxygen (commercial) is found in a cylinder that is black-coloured. The chemical formula for Acetylene can be described as C₂H₂.

It is formed by bringing calcium carbide into contact with water. Calcium carbide is a chemical compound made up of carbon and calcium metals. Carbon is the carbon atom. one atom of calcium from metal can be found in a single calcium carbide molecule. The chemical formula of Calcium carbide can be described as CaC₂.

If calcium carbonate comes into contact with water, the carbon in carbide reacts with one atom of hydrogen from the water and creates acetylene gas. CaC₂ + H₂O = CaO +C₂H₂. The main impurity present is present in the commercial form of calcium carbide CaO that reacts with water in accordance with the reaction CaO + H₂O = Ca(OH)₂ +15.1 kg kcal/gmol.

Acetylene gas can be unstable when pressurized to high pressures, it is found inside the cylinder, dissolved into an acid called acetone. Acetone is contained within the porous asbestos, charcoal or any other substance.

Acetylene is a mixture of hydrogen and carbon in the ratio of 24 parts carbon, and 2 parts of hydrogen–92.3 percent carbon and 7.7 percent hydrogen. Carbon and hydrogen have the capability of producing high temperatures of 3,100degC to 3,300degC. It has the highest flame temperature.

The reason for its heating power is the release of huge amounts of heat, which was absorbed during the process of producing calcium carbide. Acetylene is dissolved in cylindrical cylinders at an optimum pressure of 250 lbs./sq. inch. The heat that is produced by the combination of calcium carbide and water inside the generator is referred to as “concealed heat”.

 

More about Acetone

Acetylene is the chemical compound, having the formula as C₂H₂. It is the simplest alkyne and is a hydrocarbon. Acetylene is a colorless gas (in general, the lower hydrocarbons are gaseous in nature), which is used as a chemical building block widely and also as a fuel. In the pure form of acetylene, it is unstable, and therefore, it is usually handled as a solution. Pure acetylene is odorless, but, usually, the commercial grades have a marked odor because of impurities. The systematic C₂H₂ name can be given as ethyne.

Acetylene is unsaturated as an alkyne because its two carbon atoms are together bonded in a triple bond. The carbon-carbon triple bond places all the four atoms in a similar straight line, with the CCH bond angles, as 180°.

Formula and Structure of Acetylene

The chemical formula of acetylene is C₂H₂, and its extended formula is CH≡CH. The molar mass of acetylene can be given as 26.04 g/mol-1. Besides, this is the simplest alkyne molecule, which is a functional group that is characterized by scientists, having triple bonds.

Its molecules are linear 180 degrees, with its carbon atoms hybridized sp, consequently. Also, both carbons have 2 sp orbitals, on which, one bond to the hydrogen and the other bonds to the carbons simple bond. On the other side, the triple bond, that is 2  bonds that produce between the four P orbitals without hybridization, lies orthogonal to the linear system.

In a common representation used for organic molecules, its chemical structure is represented as C₂H₂, and the acetylene structure or
the C₂H₂ structure can be given as follows.

Occurrence of Acetylene

We can find the occurrence of acetylene in nature, especially dissolved in water. A few bacteria use it as the main source in the production of acetaldehyde. We can also find this compound in natural gas and in oil wells together with crude oil and the other gasses. Moreover, it is also a part of some atmosphere of the solar planet.

Production of Acetylene

Since the year 1950, acetylene has been synthesized by the partial combustion of CH₄ (which is methane). Until 1983, around 4,00,000 tons were produced.

It was prepared by a reaction, discovered by Friedrich Wohlerthe in 1862. The hydrolysis of calcium carbide reaction can be given as follows:

[ CaC_{2} + 2H_{2}O → Ca(OH)_{2} + C_{2}H_{2} ]

The reaction represented above takes place at an extremely high temperature, approximately 2000 0C, by using an electric arc furnace.

Acetylene Properties

Let us discuss the physical and chemical acetylene properties.

Physical Properties

Acetylene is a colorless gas, which has a garlic-like odor, but it has the purest form as odorless. We dissolve the compound in acetone to ship. The Melting point (more precisely triple point, due to the equilibrium between the three phases) and sublimation (process of converting the solid to gas and vice versa without going via the liquid state) points are -80.7 0C and -84.7 0C, respectively.

The density of acetylene can be given as 1.097 g/mL-1. One can easily ignite a sooty flame. However, acetylene is miscible in acetone, water, benzene, and chloroform. It is also slightly soluble in ethanol.

Chemical Properties

Acetylene is a highly reactive chemical compound owing to its electrons in the C-C triple bond. That is why acetylene is a brilliant nucleophile. Thus, it can suffer a wide variety of reactions to obtain commercial products, such as acrylic acid, acetylide, alcohol, and a vinyl compound. We can also use it to obtain organometallic compounds when reacting with a metal such as copper.

Uses of Acetylene

Many industries use acetylene widely in the welding processes because of the high temperature of acetylene flames (33000C). Some of the countries, which are less developed, use this flame as incandescent lighting. Also, it can provide intermediates as ethylene, which is very useful in the production of polypropylene, obtained by the plastic industry.

Applications of Acetylene

Portable Lighting

The calcium carbide was used to generate acetylene, which is used in the lamps either for portable or remote applications. It was used for cavers and miners before the widespread use of incandescent lighting; it is still used by the mining industries in a few nations without the workplace safety laws; many years later, low-power or high-lumen LED lighting. Also, the carbide lamps were extensively used as headlights in early motor vehicles and as an early light source for the lighthouses.

Health and Safety Hazards

Let us look at some important health and safety hazards that are linked with acetylene.

This compound is lighter than air and is just toxic when produced by the methods that can leave other chemical compounds as impurities. Also, it ignites easily with a sooty flame. Besides, it should not be stored with oxidizing agents together. Most notably, it explodes when exposed to heat or fire.