Railway Science (Chemistry-Organic Chemistry)

CH₄ (Methane), C₂H₆ (Ethane), C₃H₆ (Propene). Homologous series is a series of compounds with similar chemical properties and some functional groups differing from the successive members by CH₂ . Carbon chains of varying lengths have been observed in organic compounds having the same general formula. Example - Homologous series of Alkanes : CH₄ , C₂H₆ , C₃H₈  (They differ from each other by -CH₂ unit).

Homologous series is a series of compounds with similar chemical properties and some functional groups differing from the successive members by CH₂ . Compounds in a homologous series often have a fixed set of functional groups, resulting in chemical and physical properties that are comparable.

Ethane- A colourless, odourless, gaseous hydrocarbon (compound of hydrogen and carbon), belonging to the paraffin series. It is used to produce ethylene. Benzene- It is a chemical that is a colorless or light yellow liquid at room temperature.
It is used to make plastics, resins, synthetic fibers, rubber lubricants, etc. Acetaldehyde (ethanal)- It used in the manufacturing of perfumes, drugs, acetic acid, flavouring agent, dyes, etc.
Ethylene- It appears as a colorless gas with a sweet odor and taste. It is lighter than air. It is a ripening hormone produced by the plant. Acetone- Used in nail polish remover, paint remover, and varnish remover.

Homologous series - a sequence of compounds with the same functional group and similar chemical properties, differ by molecular formula of CH₂ and molecular mass of 14u. So the compound of C₆H₁₀ (Cyclohexene) can be found by adding CH₂. Alkane: Carbon - carbon single bond, Alkene: at least one Carbon - carbon double bond, Alkyne: at least one Carbon - carbon triple bond.

Single bond - chemical bond between two atoms involving two valence electrons. Cyclopentane (also called C pentane) - highly flammable alicyclic hydrocarbon (chemical formula C₅H₁₀). It is formed by cracking cyclohexane in the presence of alumina at a high temperature and pressure. single bonds in cyclopropane (C₃H₆) - 9.

Chemical compounds that have identical chemical formulas but differ in properties and the arrangement of atoms in the molecule are called Isomers. Isomers of Butane (C₄H₁₀): n-butane and isobutane. Isomers of Pentane (C₅H₁₂): n-pentane, Iso-pentane and neo-pentane. Isomers of other alkanes: CH₄ - 1, C₂H₆ - 1, C₃H₈ - 1, C₆H₁₄ - 5, C₇H₁₆ - 9, C₈H₁₈ - 18, C₉H₂₀ - 35, C₁₀H₂₂ - 75. Other isomeric pairs: Butane and 2-methylpropane, hexane and 2-ethyl pentane, etc.

Functional Groups - Substituent atoms or groups of atoms that are attached to specific molecules. Examples - R-COOH (Carboxylic Acid), R-COO-R’ (Ester), R-CH=O (Aldehyde), R-O-R’ (Ether), etc.

It is often restricted to the liquid form, commonly called crude oil. But petroleum also includes natural gas and the viscous or solid form known as bitumen, which is found in tar sands.
Bitumen - A substance produced through the distillation of crude oil, used in the construction industry, notably for roads and highways.

Alkanes (CₙH₂ₙ ₊ ₂) - series of compounds that contain carbon and hydrogen atoms with single covalent bonds. These are known as saturated hydrocarbons, Examples - Methane (CH₄), Ethane (C₂H₆), Propane (C₃H₈), Butane (C₄H₁₀), etc. Covalent Bond - formed by the equal sharing of electrons from both participating atoms. Ionic
Bond - form between two or more atoms by the transfer of one or more electrons between atoms.

In organic homologous series, the higher members show the higher melting and boiling point due to the London dispersion forces. For example in the homologous series of alkanes, the boiling point of butane is higher than the boiling point of propane.