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प्रश्न
Define a homologous series. Give the name and structural formula of one homologue of the following:
CH3OH
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उत्तर
Homologous series: A series of organic compounds having similar structures and chemical properties and in which the successive compounds differ by -CH2 group is called a homologous series. A homologue of CH3OH will differ by the -CH2 group; therefore, methanol's successive homologue will be ethanol (C2H5OH).
The structural formula of ethanol is as follows:
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संबंधित प्रश्न
State any four characteristics of a homologous series
Write the molecular formula of first two members of homologous series having functional group – OH
Give the structural formula for 1, 2-dichloroethane
What is the next higher homologue of methanol (CH3OH)?
An organic compound having the molecular formula C3H6O can exist in the form of two isomers A and B having different functional groups. The isomer A is a liquid which is used as a solvent for nail polish. The isomer B is also a liquid. An aqueous solution of one of the lower homologues of B is used for preserving biological specimens in the laboratory
(a) What is compound A?
(b) Write the electron-dot structure of A.
(c) What is compound B?
(d) Write the electron-dot structure of B.
(e) Name the lower homologue of compound B which is used in preserving biological specimens.
Give the dot diagram of the first member of the alcohol.
Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their (i) physical properties, and (ii) chemical properties.
What is a homologous series?
The unsaturated hydrocarbons containing a carbon-carbon double bond are called _______.
The phenomenon in which compounds having different structural formulae have the same molecular formula is called _______.
Complete the following table for the homologous series of alkanes.
| Name | Molecular formula | Condensed structural formula | Number of carbon atom | Number of -CH2- units | Boiling point °C |
| Methane | CH4 | CH4 | 1 | 1 | -162 |
| Ethane | C2H6 | CH3–CH3 | 2 | 2 | -88.5 |
| Propane | C3H8 | CH3–CH2–CH3 | 3 | 3 | -42 |
| Butane | C4H10 | CH3–CH2–CH2–CH3 | ______ | ______ | 0 |
| Pentane | C5H12 | CH3–CH2–CH2–CH2–CH3 | ______ | ______ | 36 |
| Hexane | C6H14 | CH3–CH2–CH2–CH2–CH2–CH3 | ______ | ______ | 69 |
Complete the following table for homologous series of Alkenes.
| Name | Molecular formula | Condensed structural formula | Number of carbon atom | Number of -CH2- units | Boiling point °C |
| Ethene | C2H4 | CH2 = CH2 | 2 | 0 | -102 |
| Propene | C3H6 | CH3–CH = CH2 | 3 | 1 | -48 |
| 1-Butene | C4H8 | CH3–CH2–CH = CH2 | ______ | ______ | -6.5 |
| 1-Pentene | C5H10 | CH3–CH2–CH2–CH = CH2 | ______ | ______ | 30 |
Observe the structural formula and answer the following questions.
- Write the name of the given hydrocarbon.
- The given hydrocarbon is included in which type of hydrocarbon?
- What is the kind of compounds with the above characteristic structure called?
Complete the following chart by using examples given in brackets.
(isobutylene, cyclohexane, propane, cyclohexene, cyclopentane, benzene, propyne, isobutane, propene)
| Straight chain hydrocarbons | Branched chain hydrocarbons | Cyclic hydrocarbons |
The first member of alkyne homologous series is
Write the chemical formula of two consecutive homologous of organic compounds having functional group - OH.
What happens to the (i) boiling point and (ii) solubility of organic compounds of a homologous series as the molecular mass increases?
Consider the carbon compounds having following molecular formula:
(i) C3H6 (ii) C3H8 (iii) C4H6 (iv) C6H6 (v) C6H12
- State the number of double covalent bonds present in C3H8.
- Write the formula of first member of the homologous series to which the carbon compound C4H6 belongs.
- Which one of the above compounds forms a ring structure of carbon atoms?
- Identify, which of the above compounds, is a member of alkane series.
Name the following:
Group of organic compounds where the successive members follow a regular structural pattern, successive compounds differ by a 'CH2' group.
