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प्रश्न
What is a homologous series?
What is a homologous series? Explain with an example.
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उत्तर १
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.
उत्तर २
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.
APPEARS IN
संबंधित प्रश्न
Write the next homologue of the following: C2H4
Write the molecular formula of first two members of homologous series having functional group −Br.
Fill in the following blank with suitable word:
Ethene and ethyne are examples of ..... hydrocarbons.
Give the molecular formula of one homologue of each of the following:
C2H6
Give the dot diagram of the first member of the alcohol.
.
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?
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.
Complete the correlation:
Alkene : C = C :: Alkyne: _______.
The general molecular formula for the homologous series of alkynes is _______.
Cyclohexane : Cyclic hydrocarbon : : Isobutylene : _______
As one ascends in any homologous series, physical properties change gradually.
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?
A carbon compound ‘A’ having melting point 156K and boiling point 351K, with molecular formula C2H6O is soluble in water in all proportions.
- Identify ‘A’ and draw its electron dot structure.
- Give the molecular formulae of any two homologues of ‘A’.
Define 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.
Name and draw the electron dot structure of first homologue of alkynes series.
