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प्रश्न
Write a short note.
Homologous series
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उत्तर
- The series of carbon compounds formed by joining the same functional group in the place of a particular hydrogen atom on the carbon chains having sequentially increasing length is called homologous series.
- There are different homologous series in accordance with the functional group. For example, homologous series of alcohols, homologous series of carboxylic acids, homologous series of aldehydes, etc.
- All the members of the homologous series are homologues of each other and they can be represented by the same general molecular formula.
- Physical properties generally show a gradual change with the increase in molecular mass in the series whereas chemical properties of the members of the series show similarity because of the presence of the same functional group in them.
APPEARS IN
संबंधित प्रश्न
What is meant by homologous series of carbon compounds?
Write the name and formula of the 2nd member of homologous series having general formula CnH2n.
Fill in the following blank with suitable word:
Carbon compounds have usually ... melting points and boiling points because they are ...... in nature.
What is the next higher homologue of methanol (CH3OH)?
What is the difference between two consecutive homologues:
(1) in terms of molecular mass?
(2) in terms of number and kind of atoms per molecule?
Give the molecular formula of one homologue of each of the following:
C2H6
The molecular formula of an organic compound is C18H36. Name its homologous series.
The molecular formula of a homologue of butane is:
(a) C4H8
(b) C3H6
(c) C4H6
(d) C3H8
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 abbreviated formula of the third member of the alcohol.
Give three points to differentiate between saturated and unsaturated
hydrocarbons.
While going in an increasing order there is a rise in the molecular mass of the consecutive members of the homologous series by _______.
Complete the following table for homologous series of alcohols.
| Name | Molecular formula | Condensed structural formula | Number of carbon atom | Number of -CH2- units | Boiling point °C |
| Methanol | CH4O | CH3-OH | 1 | 1 | 63 |
| Ethanol | C2H6O | CH3–CH2-OH | 2 | 2 | 78 |
| Propanol | C3H8O | CH3–CH2–CH2-OH | ______ | ______ | 97 |
| Butanol | C4H10O | CH3–CH2–CH2–CH2–OH | ______ | ______ | 118 |
Which of the following pairs can be the successive members of a homologous series?
C3H8 belongs to the homologous series of ______.
Which of the following does not belong to the same homologous series?
The first member of alkyne homologous series is
Study and complete the following table:
| Homologous series | Alkane | Alkyne |
| General formula | CnH2n+2 | 1. ______ |
| IUPAC name | 2. ______ | Ethyne |
| Common name | Marsh gas | 3. ______ |
Name the third homologue of alcohols.
Name the following:
Group of organic compounds where the successive members follow a regular structural pattern, successive compounds differ by a 'CH2' group.
