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Question
What is a homologous series?
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Solution
A homologous series is a group of organic compounds having a similar structure and similar chemical properties in which the successive compounds differ by a CH2 group.
Example:
HCOOH - Methanoic acid
CH3COOH - Ethanoic acid
CH3CH2COOH - Propanoic acid
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RELATED QUESTIONS
Write the name and formula of the 2nd member of homologous series having general formula CnH2n.
Write the molecular formula of first two members of homologous series having functional group −Br.
Give the molecular formula of one homologue of the following:
C3H6
The molecular formula of an organic compound is C18H36. Name its homologous series.
The number of carbon atoms present in the molecule of fifth member of the homologous series of alkynes is:
(a) four
(b) five
(c) six
(d) seven
What is the difference in the molecular formula of any two adjacent homologues:
(i) In terms of molecular mass
(ii) In terms of number and kind of atoms per molecule?
The phenomenon in which compounds having different structural formulae have the same molecular formula is called _______.
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?
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.
