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Questions
What is a homologous series?
What is a homologous series? Explain with an example.
Solution 1
Homologous series is a group of organic compounds with a similar structure and similar chemical properties in which the successive compounds differ by a CH2 group.
Solution 2
A homologous series is a series of carbon compounds that have different numbers of carbon atoms but contain the same functional group.
For example, methane, ethane, propane, butane, etc. are all part of the alkane homologous series. The general formula of this series is CnH2n+2.
Methane CH4
Ethane CH3CH3
Propane CH3CH2CH3
Butane CH3CH2CH2CH3
It can be noticed that there is a difference of -CH2 unit between each successive compound.
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RELATED QUESTIONS
Write the molecular formula of first two members of homologous series having functional group -Cl.
Write the molecular formula of first two members of homologous series having functional group – OH
Write the molecular formula of the 2nd and 3rd member of the homologous series where the first member is ethyne.
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)?
By how many carbon atoms and hydrogen atoms do any two adjacent homologues differ?
What is a homologous series? Explain with an example.
The molecular formula of a homologue of butane is:
(a) C4H8
(b) C3H6
(c) C4H6
(d) C3H8
The molecular formula of the third member of the homologous series of ketones is:
(a) C4H8O
(b) C3H6O
(c) C5H10O
(d) C6H12O
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 structure of the second member of the alcohol group
Define homologous series of organic compounds. List its two characteristics. Write the name and formula of the first member of the series of alkenes.
Give the names of the first four members of the homologous series of
alkynes.
Copy and complete the following table which relates to three homologus series of hydrocarbons:
| General formula | CnH2n | CnH2n-2 | CnH2n+2 |
| IUPAC name of the homologus series | |||
| Characteristic bond type | Single bonds | ||
| IUPAC name of the first member of the series | |||
| Type of reaction with chlorine | Addition |
Two statements are given - one labeled Assertion (A) and the other labeled Reason (R).
Assertion (A): In a homologous series of alcohols, the formula for the second member is C2H5OH and the third member is C3H7OH.
Reason (R): The difference between the molecular masses of the two consecutive members of a homologous series is 144.
The general molecular formula for the homologous series of alkynes is _______.
Find the odd one out and give its explanation.
There are different general molecular formula for all members of the homologous series.
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 |
What is called homologous series? Give any three of its characteristics?
Which of the following does not belong to the same homologous series?
C3H8 belongs to the homologous series of ______.
The first member of alkyne homologous series is
Name the following organic compound:
The first homologue whose general formula is CnH2n.
Name and draw the electron dot structure of first homologue of alkynes series.
Name the third homologue of aldehydes.
Name the following:
Group of organic compounds where the successive members follow a regular structural pattern, successive compounds differ by a 'CH2' group.
