Unsaturated Hydrocarbon

Dhristi JEE 2022-24

What is Unsaturated Hydrocarbon?

We are completely aware that an organic compound is made up of carbons and hydrogen atoms. But unsaturated carbons state that adjacent carbon atoms have formed either a double or triple bond with each other. To make them saturated, we need to add more hydrogen atoms to them.


These unsaturated ones can be in the form of straight-chain or branched chains or aromatic compounds. The ones which have at least one double bond between carbon atoms are known as alkenes. But if there is at least one triple bond between carbons in an organic compound, they are alkynes. Below you will understand different types, examples, and the uses of Unsaturated Hydrocarbons in detail.


What are Hydrocarbons? Give Examples.

An organic compound is a hydrocarbon when it contains carbon and hydrogen atoms in it. These can be either saturated or unsaturated. Saturated ones are those having a single bond between two carbon atoms or with a hydrogen atom. Unsaturated ones are those which have either a double or triple bond with two adjacent carbon atoms.


Some basic saturated hydrocarbon examples are methane and ethane. Unsaturated Hydrocarbon examples are Ethene and Ethyne.


What are Different Types of Unsaturated Carbon Compounds?

According to the basic unsaturated hydrocarbon definition, there are three different types. These are:

  • Alkenes

  • Alkynes

  • Aromatic

The classification is based upon the type of carbon-carbon bond in the compound. Also, it is defined by its basic structure.

  • If there is at least one double bond between two adjacent carbon atoms in a hydrocarbon, those are alkenes or olefins. Ethene is an example of such a type given by \[C_{2}H_{4}\]. These will have only one double bond with no functional groups. The basic formula is given by \[C_{2}H_{2n}\].


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  • In Alkynes, there is at least one triple bond between two adjacent carbon atoms. An example of such a kind is acetylene given by \[C_{2}H_{2}\]. The basic unsaturated hydrocarbon formula for alkynes is given by \[C_{2}H_{2n - 2}\].


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If you want to check if a particular hydrocarbon is unsaturated, you can add bromine water to it. In case water turns decolourised, it is unsaturated. If it forms a precipitate, then it is phenol. Also, benzene is the one that will not decolorize bromine water. 


What are the Different Uses of Unsaturated Carbon Compounds?

Uses of compounds listed among unsaturated category are:

  • It is the usual case of ripening fruits with the help of alkenes.

  • In chemistry, we include unsaturated carbons to synthesize various compounds. They are usually used as monomers in such areas.

  • Mustard gas is prepared with the help of alkenes which is often required for chemical warfare. It is poisonous.

  • Acetylene is the fuel used inside a torch that we generally use in a home project.

  • Unsaturated compounds are generally used in the manufacturing of plastics.

  • Alkenes are used in industries for synthesizing fuel, detergent, plastic, and alcohol.

  • The use of Polystyrene is generally for disposable cups, egg cartons, and other convenient products.


Physical Properties of Unsaturated Carbon

  • As talked about above, unsaturated compounds have either one double or triple bond. These are generally given by the formula \[C_{2}H_{2n}\] and \[C_{2}H_{2n - 2}\].

  • To make unsaturated as saturated compounds, we need to add hydrogen atoms to them. This will form more carbon and hydrogen bonds.

  • The carbon-carbon bond formed in a double bond of carbons will form 120 degree angles.

  • The carbon-carbon bond formed in the triple bond of carbons will form 180 degree angles.

  • Unsaturated compounds get through different reactions, including combustion reactions, addition reactions, oxidation reactions performed by alkenes, polymerization of alkenes.

  • Combustion reactions include the formation of carbon dioxide and water.

  • The addition reaction is either symmetrical or unsymmetrical.

  • Oxidation Reactions include either addition of oxygen in a molecule or the removal of hydrogen from a molecule.

  • If reactions are conducted under pressure at a particular temperature with the help of a catalyst, these are polymerization reactions. The molecules produced are polymers.

  • The most common example of aromatic compounds universally considered is benzene. It forms 120 degrees between constituent carbon atoms.


Saturated Vs Unsaturated Hydrocarbons:

Both the compounds are organic compounds i.e, made up of hydrogen and carbon atoms. The major difference between both is the type of bonds they form. Saturated hydrocarbons have one covalent carbon bond, for example, methane, propane, and butane are some of the saturated hydrocarbons as they have a single carbon covalent bond and unsaturated hydrocarbons on the other hand have either a double covalent carbon bond or a triple covalent carbon bond. 


Unsaturated hydrocarbons are further divided into alkenes and alkynes based on the number of covalent bonds that the carbon atoms form. The hydrogenation reaction is the test used to figure out whether a compound is a saturated hydrocarbon or an unsaturated hydrocarbon. Hydrogenation is a type of reduction reaction where a hydrogen atom is added to a particular compound to know whether it is saturated or unsaturated. When the hydrogen atom is added to a compound it gets saturated and it tells us the previous stage of the compound. 


The above article has discussed different properties, types, and uses of unsaturated hydrocarbons. Surely, this will help you understand and clarify your concepts on the topic.

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FAQs (Frequently Asked Questions)

1. Are Alkynes Unsaturated Compounds in Organic Compounds?

According to the basic unsaturated hydrocarbon definition, there must be at least one double or a triple bond between two adjacent carbons in an organic compound. Alkynes have at least one triple bond between two adjacent carbon atoms. Thus these are unsaturated compounds. These have the triple bond; thus, the naming convention is given by “-one” as the suffix. The basic formula for alkynes is given by \[C_{2}H_{2n - 2}\]. These are made up of functional groups with a traditional name as acetylene. As compared to other hydrocarbons, alkynes are hydrophobic. These have formed a maximum carbon-carbon bond. Thus in terms of bond strength, it is given by 839 kJ/mol. This is very hard to break.

2. Are Unsaturated Hydrocarbons Good for You?

As compared to saturated compounds, unsaturated carbons are healthier—these help in removing the level of bad cholesterol present in our body. This helps in improving blood circulation on a good scale. You are not prompted to form heart disease with such compounds and also reduces inflammation in your body. Unsaturated ones are affluent in polyunsaturated fats. Thus they also bring Vitamin E into your diet, which is highly required for good body growth. Your body is not on the verge of forming rheumatoid arthritis. These compounds bring good development in your body cells and introduce an antioxidant diet to your body. These compounds are known to provide body nourishment.

3. What are unsaturated hydrocarbons?

All the organic material around us is made up of hydrocarbons which are different combinations of hydrogen and carbon atoms. Unsaturated hydrocarbons are one such compound in which the carbon atoms have formed double or triple bonds and to make them stable and saturated, we should add more hydrogen atoms. The alkenes in hydrocarbons have one double bond and the alkynes have triple bonds. Cyclic hydrocarbons which have at least one double bond or a triple bond are also considered unsaturated hydrocarbons. For example, propane, ethene, ethyne are some unsaturated hydrocarbons. When a compound is less saturated, it is more active and bonds easily with other elements or compounds and if the compound is saturated, it is less active and can not react with other compounds and elements easily.

4. What are the applications of hydrocarbons in real life?

Hydrocarbons are made up of hydrogen and carbon elements in different combinations. They are the base that forms the entire organic world around us. Based on the combinations and bonds formed, hydrocarbons are divided into saturated and unsaturated hydrocarbons and are further divided into alkenes, alkynes, etc, Following are some of the applications of Hydrocarbons in real life:


Hydrocarbons are an energy source when they are combusted and are cheaply available in the market as a fuel resource


The amount of carbon dioxide they release when they are burnt can be controlled by us

PETE, HDPE, etc are used to make plastic items like cups, bottles, etc 


Methane is an alkane that is used to generate electricity and it is generally produced from the waste generated in landfills and urban areas. When the bacteria decompose the waste material, methane is produced and it is further processed to generate electricity. 


Hexane is another such alkane that is used as glue in the leather and footwear industry to form layers of the material


Coal, petroleum, and natural gas are formed with different mixtures of hydrocarbons and are the major source of energy not only for India but also for many developing countries. But this source is not sustainable as it releases harmful gases and is also a limited source.

5. What is the difference between saturated and unsaturated hydrocarbons?

Hydrocarbons are organic compounds that have different combinations of hydrogen and carbon atoms. They are divided into saturated and unsaturated hydrocarbons. The main difference between saturated and unsaturated hydrocarbons is the bond formed by carbon atoms. In saturated hydrocarbons, carbon atoms form only one covalent bond between the carbon atoms present, and in unsaturated hydrocarbons, carbon atoms form either two covalent bonds or a triple covalent bond. 


If the carbon makes a double covalent bond, they are called alkenes and if they form a triple covalent bond, they are called alkyne. For example, ethene is an alkene that has a double covalent bond and ethylene is an example of alkyne which has a triple covalent bond. Whereas ethane has only one covalent bond and is a saturated hydrocarbon. To read more about hydrocarbons, their types, subtypes, examples, structure, and application in real-life, please visit Vedantu.

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