Chemistry
Explain the term – 'Hydrocarbons'. State the two main groups of hydrocarbons with examples. Draw a chart differentiating — 'Alkanes, Alkenes and Alkynes' — with respect to:
- General formula
- Characteristic bond
- IUPAC and the common name of the first three members and condensed/branched/electronic structural formula of each
- Availability of electrons
- Reactivity
- Characteristic reaction.
Answer
Hydrocarbons — Hydrocarbons are compounds that are made up only of carbon and hydrogen atoms.
Classification of Hydrocarbons — Hydrocarbons are sub-divided into two main groups, the aliphatic (open) and cyclic (closed) chain compounds. The open chain compounds or aliphatic hydrocarbons are further sub-divided into saturated hydrocarbons and unsaturated hydrocarbons. Example of saturated hydrocarbons is the homologous series of Alkanes. Examples of unsaturated hydrocarbons are the homologous series of Alkenes and Alkynes.
| Alkanes | Alkenes | Alkynes | |
|---|---|---|---|
| General formula | CnH2n+2 | CnH2n | CnH2n-2 |
| Characteristic bond | Contains a single C – C covalent bond | Contains a double C = C covalent bond | Contains a triple C≡C covalent bond |
| IUPAC Name of first 3 members | Methane, Ethane, Propane | Ethene, Propene, 1-Butene | Ethyne, Propyne, 1-Butyne |
| Common Name of first 3 members | Methane, Ethane, Propane | Ethylene, Propylene, 1-Butylene | Acetylene, Methyl acetylene, Ethyl acetylene |
| Condensed Structural Formula |  |  |  |
| Branched Structural Formula |  |  |  |
| Availability of electrons | Not available | Available | Available |
| Reactivity | Less reactive | More reactive | Most reactive |
| Characteristic Reaction | Substitution reaction | Addition reaction | Addition reaction |
Related Questions
Explain the terms — 'Isomers' and 'Isomerism'. State the 'Characteristics of isomers' with reference to —
- Properties of isomers
- Number of isomers with relation to carbon atoms in the isomer.
Differentiate between — 'Chain isomerism' and 'Position isomerism ' — with suitable examples.
Draw the structural formula of each of the following :
Alkane
(a) Methane
(b) Ethane
(c) Propane
(d) Butane — chain isomers
(i) 1-butane [n-butane]
(ii) 2-methyl propane [iso-butane](e) Pentane — chain isomers
(i) 1-pentane [n-pentane]
(ii) 2-methyl butane [iso-pentane]
(iii) 2-2-dimethylpropane [neo-pentane]Explain the term – 'Nomenclature'. State it's need with reference to organic compounds. State the basic rules of Nomenclature by the trivial system with suitable examples. Explain the longest chain rule and the smallest number for functional groups rule of Nomenclature by the IUPAC system with suitable examples.
Draw the structural formula of each of the following :
Alkene
(a) No corresponding alkene
(b) Ethene
(c) Propene
(d) Butene — Position isomers
(i) 1-butene
(ii) 2-butene
— Chain isomer
(i) 2-methyl prop-1-ene(e) Pentene — Position isomers
(i) 1-pentene (i) 2-pentene — Chain isomer
(i) 2-methyl but-1-ene
(ii) 3-methyl but-1-ene