Acetylene or ethyne is an organic chemical compound of an alkyl group. It is the simplest alkyne and hydrocarbon. Their wide use is as a fuel and chemical building block. Also, in it its purest form it is unstable that’s why it is commonly handled as a solution. Due to impurities, the commercial-grade acetylene has a striking odor. Edmund Davy discovered it in 1836, who identified it as a “new carburet of hydrogen”. Later on, the French chemist Marcellin Berthelot rediscovered it 1860 and coined the name acétylène. Learn acetylene formula here.
Acetylene formula and structure
Its chemical formula is C2H2, and the extended formula is CH≡CH. The molar mass of acetylene is 26.04 g/mol-1. In addition, this molecule is the simplest alkyne, which is a functional group that scientists characterize by having triple bonds.
Its molecules are linear (180 degrees), consequently with its carbon atoms hybridized sp. Moreover, both the carbon has 2 sp orbitals, one of which bonds to the hydrogen and the other for the carbons simple bond, whereas the triple bond, that are 2 Π bonds, that form between the four orbitals P without hybridization that is orthogonal to the linear system. In the common representation used for organic molecules, its chemical structure can be represented as below:
In nature, we can find it especially dissolved in water. Some bacteria use it as the main source to produce acetaldehyde. We can also find it in natural gas, and in oil wells together with crude oil and other gases. Furthermore, it is also a part of some solar planet’s atmosphere.
Generally, we can find it in natural gas and oil wells gases. But we can also produce it by the combustion or electric arc of hydrocarbons such as methane and ethane or even from the crude oil. Furthermore, this process results in a mixture of gases, so that the acetylene necessarily be separated from the chemical industry process.
Besides, the production of calcium carbide requires extremely high temperatures, ~2000 °C, hence making it necessary to use an electric arc furnace.
Acetylene Physical Properties
It is a colorless gas that has a garlic-like odor but its purest form is odorless. We dissolve it in acetone to ship. The Melting point (more correctly triple point because of the equilibrium between the three phases) and sublimation (the process of converting solid to gas and vice versa without going through liquid state) points are -80.7oC and -84.7oC, respectively.
The density of acetylene is 1.097 g/mL-1. You may easily ignite a sooty flame. However, acetylene is miscible in water, acetone, chloroform, and benzene. Also, it is slightly soluble in ethanol.
Acetylene Chemical Properties
It is a highly reactive chemical compound owing to its Π electrons in the C-C triple bond, that’s why acetylene is a brilliant nucleophile. Hence, it can suffer a wide variety of reactions to obtain commercial products, such as acetylide, acrylic acid, a vinyl compound, and alcohol. We can use it to obtain organometallic compounds when reacts with metal like copper.
Industries widely use it in the welding processes due to the high temperature of acetylene flames (3300oC). Some lesser developed countries use this flame as incandescent lighting. Moreover, it can also provide intermediates as ethylene very use is in the production of polypropylene by the plastic industry.
Health and safety hazards
It is lighter than air and it is just toxic when produced by methods that can leave other chemical compounds as impurities. Furthermore, it easily ignites with a sooty flame. Moreover, it should not be stored together with oxidizing agents. Most importantly, it explodes when exposed to fire or heat.
Solved Example For You
Question: How to prepare acetylene by hydrolysis?
Solution: We can prepare acetylene by hydrolysis of calcium carbide:
CaC2 + 2H2O → Ca(OH)2 + C2H2