What is Ethyne Definition Molecular Formula Preparation and Chemical Reactions
Build Your Concept By Referring to this Page Describing Ethyne
Organic chemistry is a universe of organic compounds. Studying their complex structures and behaviour is quite fascinating. In this segment, we will elaborately study Ethyne. It is also called acetylene. The triple bonded two carbon organic compound that behaves like gas at room temperature is called ethyne. The common name of ethyne is acetylene. The chemistry experts of Vedantu have scribed this concept page for the new learners. It falls in the hydrocarbon part of the organic chemistry chapters that should be properly studied to prepare a foundation. Refer to this page when you are studying ethyne and find an organized presentation of its structure, preparation, and chemical properties.
What is Ethyne or Acetylene?
Ethyne is the simplest triple-bonded 2 carbon organic compound, also known as acetylene. The IUPAC name of acetylene is ethyne. ‘Eth’ means ‘two’ and ‘yne’ means a triple bond between two carbon atoms. Together they make the IUPAC name and the meaning of ethyne. The acetylene formula is C2H2. As you can easily understand from the formula that it is a hydrocarbon as there are no elements other than carbon and hydrogen in the molecular structure.
Acetylene Structural Formula
The structure of ethyne makes it unstable in pure form. As per the structural formula of ethyne, the tension in the triple bond makes the carbon atoms increases as the bond angle is almost 180o. The length of the C-H bond is just 106 picometers whereas the C-C bond length is 120.3 picometers. It is an unsaturated hydrocarbon that cannot remain stable when stored in pure form. Every carbon atom is connected with a hydrogen atom at one end by a single bond and with another carbon atom with a triple bond. It is a symmetrical compound.
Another interesting aspect to learn on this concept page is the electron dot structure of ethyne. You will have to study and practice the electron dot structure of acetylene properly so that you can understand how the electrons are shared in every bond present in the molecule. Practising the electron dot structure will also help students understand how the compound is formed. This is also called the ethyne Lewis structure. This particular concept is ideal for students to understand how organic bonds are formed by sharing electrons. You will also learn how a carbon-hydrogen bond is formed and how the electrons are shared between two atoms of different elements.
Preparation of Ethyne
Now that you have studied the ethyne formula, let us move to the section where it is prepared. Study this section to understand how the triple bond is formed between the two carbon atoms. There are different ways to prepare acetylene. Ethyne can be prepared when methane is subjected to partial combustion at high pressure. Two methane (CH4) molecules connect forming a triple bond when the hydrogen atoms in the molecules get removed. The easiest way to prepare acetylene is by hydrolyzing calcium carbide (CaC2) simply in presence of water. Calcium carbide, also known as, calcium acetylide, quickly breaks in the presence of water due to the unstable bond and electron tension between the carbon molecules. The equation of this reaction is:
H2O + CaC2 → C2H2 + Ca(OH)2
If you consider the acetylene chemical formula, you will find that it is the final product along with calcium hydroxide. This is how acetylene is industrially produced on a large scale very easily and used for different purposes. You can now easily answer the question of how is ethyne prepared.
Properties of Acetylene/Ethyne
Let us proceed to the properties of ethyne. The physical and chemical properties of ethyne are:
The molecular mass or molar mass of this compound is 26.083 grams. You can also calculate it when you add the atomic mass of all the atoms in the molecular formula of acetylene.
Ethyne, under the standard condition of temperature and pressure (STP), behaves like a colourless gas. It also does not have any distinct odour.
The density of this gas is 1.097 g/l.
As you understood from the properties of ethyne that it is a gas, its melting point is -80.8°C or 192.3K.
Ethyne slightly dissolves in water.
FAQs on Ethyne Structure Properties Reactions and Applications
1. What is ethyne?
Ethyne is the simplest alkyne with the molecular formula C2H2 and contains a carbon–carbon triple bond. It is also commonly known as acetylene in industry and laboratory use.
- Structure: H–C≡C–H
- Hydrocarbon type: Unsaturated hydrocarbon
- Hybridization of carbon: sp
- Bond angle: 180° (linear geometry)
2. What is the chemical formula and structure of ethyne?
The chemical formula of ethyne is C2H2, and its structure contains a carbon–carbon triple bond (C≡C).
- Structural formula: H–C≡C–H
- Each carbon forms one σ bond with hydrogen and one σ + two π bonds with the other carbon.
- Molecular geometry: Linear due to sp hybridization.
3. Why is ethyne called an alkyne?
Ethyne is called an alkyne because it contains at least one carbon–carbon triple bond (C≡C). Alkynes are a homologous series of unsaturated hydrocarbons with the general formula CnH2n−2.
- For ethyne: n = 2
- General formula gives: C2H2
- Presence of C≡C defines it as an alkyne.
4. How is ethyne prepared in the laboratory?
Ethyne is prepared in the laboratory by reacting calcium carbide with water. The reaction produces ethyne gas and calcium hydroxide.
- Balanced equation:
- The gas is collected over water.
- This method is commonly used in school laboratories.
5. What are the physical properties of ethyne?
Ethyne is a colorless, highly flammable gas with a faint characteristic odor.
- Molecular mass: 26 g mol−1
- State at room temperature: Gas
- Slightly soluble in water
- Burns with a luminous, sooty flame
6. What happens when ethyne burns in oxygen?
Ethyne undergoes complete combustion in oxygen to form carbon dioxide and water.
- Balanced equation:
- The reaction is highly exothermic.
- Produces a very hot flame (used in oxy-acetylene welding).
7. What are the chemical properties of ethyne?
Ethyne mainly undergoes addition reactions due to its carbon–carbon triple bond. Important chemical reactions include:
- Hydrogenation: C2H2 + 2H2 → C2H6 (in presence of Ni catalyst)
- Halogenation: Adds Br2 or Cl2 across the triple bond.
- Hydration: Forms ethanal (CH3CHO) in presence of H2SO4 and HgSO4.
- Polymerization: Forms polyacetylene under suitable conditions.
8. What is the hybridization of carbon in ethyne?
Each carbon atom in ethyne is sp hybridized. In sp hybridization:
- One s orbital mixes with one p orbital.
- Two sp hybrid orbitals are formed.
- Bond angle becomes 180° (linear geometry).
9. What is the difference between ethane, ethene, and ethyne?
Ethane, ethene, and ethyne differ in the type of carbon–carbon bond and degree of saturation.
- Ethane (C2H6): Single bond (alkane), saturated.
- Ethene (C2H4): Double bond (alkene), unsaturated.
- Ethyne (C2H2): Triple bond (alkyne), more unsaturated.
10. What are the uses of ethyne?
Ethyne is mainly used in oxy-acetylene welding and as a chemical feedstock in organic synthesis. Major uses include:
- Oxy-acetylene flame: Produces temperatures above 3000°C for welding and cutting metals.
- Manufacture of chemicals such as vinyl chloride and synthetic rubber.
- Preparation of aldehydes and other organic compounds.
