[Chemistry Class Notes] on Unsaturated Hydrocarbon Pdf for Exam

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:

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.