Hydrocarbons are organic compounds, and there are many hydrocarbons used in our daily life. This article covers the basic notes on hydrocarbon and its compounds. This is especially for secondary level for any syllabus but can be used as a reference for studying or teaching material.
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There are different types of compounds around us. These compounds can be classified as carbonic and non-carbonic compounds or organic and non-organic compounds. The compounds that are obtained from the minerals are known as non-carbonic compounds and those compounds that are obtained from plant and animal sources are known as carbonic compounds.
All the compounds of carbon except its oxides, carbonates, bicarbonates, and carbides are organic compounds. The carbonic compounds composed of only carbon and hydrogen are called hydrocarbons.
Hydrocarbon
Hydrocarbon is an organic compound composed of carbon and hydrogen and is a chief component of petroleum and natural gas. Hydrocarbons are combustible and organic.
Properties of hydrocarbons
Following are some of the properties of hydrocarbons.
- Hydrocarbons are usually colorless and hydrophobic.
- Hydrocarbon compounds possess weak intermolecular forces of attraction.
- Hydrocarbons have relatively low melting and boiling temperature.
- They only dissolve in organic solvents and are insoluble in water or any other polar solvents.
- They have a faint odor similar to gasoline or lighter fluid.
- They have combustible properties.
Uses of hydrocarbons
Following are some of the uses of hydrocarbons.
- Hydrocarbons are used as fuels and lubricants.
- They are chief compounds in petroleum and natural gas.
- They are used as a raw materials for the production of plastics, fibers, rubbers, and explosives too.
- They are used for making solvents.
Organic Compounds
The compounds of carbon covalently bonded to other carbon atoms or hydrogen atoms are called organic compounds. Besides hydrogen, carbon may also form covalent bonds with other elements like oxygen, nitrogen, halogens, sulphur, and phosphorus. However, CO2, CO, HCO3 -, and CO3 – -, are not organic compounds although they contain carbon atoms. Generally, organic compounds are composed of elements like carbon, hydrogen, oxygen, nitrogen, halogen, sulphur, and phosphorus. Some organic compounds may also contain metal bonded to them. Examples of organic compounds are methane, ethane, ethene, acetylene, methanol, chloroform, urea, insulin, protein, oil, etc.
The branch of chemistry which deals with the study of these compounds is called carbonic chemistry or organic chemistry.
Petroleum is the main source of hydrocarbons. Hydrocarbons are classified as saturated and unsaturated on the basis of the types of bonds between the carbon atoms.
Saturated Hydrocarbon
The hydrocarbons that have a single covalent bond between the carbon atoms are called saturated hydrocarbons. They are very stable and less reactive so they are known as paraffin. They are also known as alkanes. The general formula of these compounds is CnH2n+2, where ‘n’ is the number of carbon atoms. Here n=1, 2, 3…
| Name | Molecular Formula | Condensed Formula |
| Methane | CH4 | CH4 |
| Ethane | C2H6 | H3C-CH3 |
| Propane | C3H8 | H3C-CH2-CH3 |
| Butane | C4H10 | H3C-(CH2)2-CH3 |
| Pentane | C5H12 | H3C-(CH2)3-CH3 |
Unsaturated Hydrocarbon
The hydrocarbons having double or triple covalent bonds between the carbon atoms are called unsaturated hydrocarbons. They are less stable and very reactive so they are known as olefins. They are also known as alkene and alkyne.
Alkene
The hydrocarbons having a double covalent bond between the carbon atoms are called alkene. Example ethene, propene, butene, etc. The general formula of these compounds is CnH2-n where ‘n’ is the number of carbon atoms.
| Name | Molecular Formula | Condensed formula |
| Ethene | C2H4 | H2C=CH2 |
| Propene | C3H6 | H3C-CH=CH2 |
| Butene | C4H8 | H3C-CH2-CH=CH2 |
Alkyne
The hydrocarbons having a triple covalent bond between the carbon atoms are called alkyne. Example ethyne, propyne, butyne, etc. The general formula of these compounds is CnH2n-2 where ‘n’ is the number of carbon atoms.
| Name | Molecular Formula | Condensed Formula |
| Ethyne | C2H2 | HC≡CH |
| Propyne | C3H4 | H3C-C≡CH |
| Butyne | C4H6 | H3C-CH2-C≡CH |
Hydrogenation
Hydrogenation is the process of making vanaspati ghee from vegetable oil. In the process of hydrogenation, the unsaturated fatty acids change to saturated fatty acids.
H2C=CH2 + H2 ——————————————————————————> C2H6
Alkene Alkane
Differences Between Saturated and Unsaturated Hydrocarbons
| Saturated Hydrocarbon | Unsaturated Hydrocarbon |
| 1. The hydrocarbon having a single covalent bond between the carbon atoms is called saturated hydrocarbon. | 1. The hydrocarbon having double or triple covalent bond between the carbon atoms is called unsaturated hydrocarbon. |
| 2. Saturated hydrocarbons are stable. | 2. Unsaturated hydrocarbons are unstable or they are chemically reactive. |
| 3. They are also known as alkanes. | 3. They are also known as alkenes and alkynes. |
Homologous Series
The series of hydrocarbons that can be represented by the same general formula is called a homologous series. Each member of the homologous series is called a homolog. All the members of the series can be represented by a common formula and the adjacent homolog of the series differs by CH2 group. Similarly, the molecular weight of adjacent members of the series of homologs differs by 14.
| Name | Molecular Formula |
| Methanol | CH3OH |
| Ethanol | CH3CH2OH |
| Propanol | CH3CH2CH2OH |
Alkyl Radical
The common group of toms formed by removing one hydrogen atom from an alkane molecule is called an alkyl radical. It can be represented by a general formula Cn H2n+1. For example – CH3+, CH3CH2+, etc.
Functional Group
An atom or a group of atoms which determines the structure and chemical reactivity of a certain group of organic compounds is called a functional group. The functional groups get attached to the alkyl groups to form different groups of organic compounds.
Example of functional groups -O-, -CHO, -COOH
Nomenclature of Hydrocarbons
IUPAC means International Union of Pure and Applied Chemistry. It is a system established by scientists to make uniformity in the names of organic and inorganic compounds all over the world. According to this system, a compound has the same or only one name. This removes the mistake while naming or understanding the compounds.
Common system of nomenclature of hydrocarbons
i. Find the word root on the basis of the number of carbon atoms as:
| No. of Carbon atoms | Word Root | No Carbon atoms |
| C-1 | Meth | C1 |
| C-2 | Eth | C2 |
| C-3 | Prop | C3 |
| C-4 | But | C4 |
| C-5 | Pent | C5 |
| C-6 | Hex | C6 |
| C-7 | Hept | C7 |
| C-8 | Oct | C8 |
| C-9 | Non | C9 |
| C-10 | Dec | C10 |
ii. In this way after finding the word root, add the suffix like ane, ‘ene’, and ‘yne’ according to the number of bonds between the carbon atoms.
For example,
CH3-CH3
There are two carbon atoms so the word roots us eth and there is only one covalent bond between the carbon atoms, so we should add ‘ane’ as the suffix.
So, its name is eth+ane = ethane
Some Important Hydrocarbons and their Compounds
Methane
This gas is found in marshy places so it is known as marsh gas. Its molecular formula is CH4. This gas is generally found above the mineral oil. It is also found in gobar gas or biogas, and sewage gases. It is colorless, odorless, and tasteless. It is not soluble in water but is soluble in organic solvents like ether, alcohol, etc.
Uses of Methane
- Methane is used for cooking food as gobar gas or biogas and as a fuel in industries.
- It is used to prepare carbon black which is used to make printing ink, shoe polish, and paint.
- Methane is also used to prepare chloroform, carbon tetrachloride, methyl alcohol, formaldehyde, etc.
- It is also used in the industrial preparation of hydrogen gas.
Ethane
Ethane is a saturated hydrocarbon having two carbon atoms bonded with a single covalent bond. Its molecular formula is C2H6. It is found along with methane gas in natural gas, coal gas, and petroleum mines. It is also colorless, odorless, and tasteless like methane. It is also insoluble in water but soluble in organic solvents like ether, alcohol, etc. Discover more about ethane.
Uses of Ethane
Following are some of the uses of ethane.
- It produces heat on combustion so it is used in metal welding.
- It is also used to prepare carbonic compounds like ethyl chloride, nitroethane, etc.
Propane
Propane is also a saturated hydrocarbon. Its molecule consists of three carbon atoms and its molecular formula is C3H8. This gas is also found in natural gas and petroleum mines. It is a colorless, and odorless gas. It is insoluble in water but is soluble in organic solvents.
Uses of Propane
- It is a highly flammable gas so it is used as a fuel.
- It is used to make different types of carbonic compounds.
- It is used as a coolant in petroleum industries.
Butane
Butane is also a saturated hydrocarbon. Its molecule consists of four carbon atoms and its molecular formula is C4H10. This gas is also found in natural gas and petroleum mines. It is a colorless, and odorless gas. It is insoluble in water but is soluble in organic solvents.
Uses of Butane
- It is used as a raw material for making synthetic rubber.
- It is mixed with methane in LPG(Liquefied Petroleum Gas) which is used as a fuel. It easily changes to liquid upon applying pressure.
Alcohol
The compounds of alcohol are produced from alkanes. The compounds formed by the replacement of one or more hydrogen atoms of alkanes by the -OH group are called alcohols. Its general formula is CnH2n+1OH. The Hydroxyl group (-OH) is the functional group of the alcohols. The alcohol with only one hydroxyl group is known as monohydric alcohol. The alcohol with two hydroxyl groups is known as dihydric alcohol and the alcohol that consists of three hydroxyl groups is known as trihydric alcohol.
Some Important Alcohol Compounds
Methyl Alcohol
Methyl alcohol is a monohydric alcohol. Its IUPAC name is methanol. Its molecular formula is CH3OH, and it is represented by CH3-OH.
Uses of Methyl Alcohol
- It is used to prepare methylated spirits.
- It is used as a solvent for paints and varnishes.
- Methanol is also used to prepare perfumes, paints, medicines, and synthetic clothes.
- It is used to manufacture formaldehyde.
- It is also used in dry cleaning.
Ethyl Alcohol
Ethyl alcohol is also a monohydric alcohol. Its IUPAC name is ethanol. Its molecular formula is C2H5OH. It is represented by CH3-CH2-OH. It is an edible alcohol drink.
Uses of Ethyl Alcohol
- Ethyl alcohol is used to prepare hard drinks like whisky, wine beer, etc.
- It is used to sterilize syringes and wounds in hospitals, health posts, and nursing homes.
- It is used to preserve biological specimens in laboratories.
- It is also used in thermometers.
- It is used in the manufacture of polyethylene, terylene, soaps, paints, dyes, etc.
Glycol
It is a dihydric alcohol, in which two hydroxyl groups are attached to each of the carbon atoms of hydrocarbons. In glycol, each carbon contains one hydroxyl group. Different types of glycols are used in industrial and food stuffs. One of the common glycols is ethane diol. Its IUPAC name is ethane-1, 2-diol. Its molecular formula is CH2OHCH2OH.
Glycerol
The compound formed by replacing three hydrogen atoms of propane with three hydroxyl groups is called glycerol. Glycerol is a tihydric alcohol which is also known as glycerine. Its name is derived from a greek word glycerol which means sweet. It is a colourless and sweet viscous liquid. It is soluble in water and alcohol but insoluble in ether. Its IUPAC name is propane -1,2,3-triol. Its molecular formula is C3H5(OH)3.
Uses of Glycerol
- It is used to protect skin by trapping moisture and preventing its dryness.
- It is used as a sweetening agent in food.
- It is used to make good quality soap, lotion, cosmetics, shaving creams, etc.
- It is used to keep the tobacco moist and it also prevents the dryness of fruits and foods as well as prevents them from decaying.
Hence, hydrocarbons are essential organic compounds composed of carbon and hydrogen that play a significant role in our daily lives. They are found in petroleum and natural gas, serving as fuels, lubricants, and raw materials for various industries. The two main types of hydrocarbons are saturated (alkanes) and unsaturated (alkenes and alkynes). Additionally, organic compounds, which contain carbon covalently bonded to other elements, have diverse applications in various fields. Understanding these fundamental concepts helps us appreciate the significance of hydrocarbons and organic compounds in our modern world.
