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प्रश्न
State any four characteristics of a homologous series
State two characteristics of a homologous series.
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उत्तर
Characteristics of a homologous series:
- Each member of the series differs from the preceding one by the addition of a -CH2 group and by 14 a.m.u.
- All members of a homologous series share the general formula.
Example: The general formula for alkane is CnH2n+2 and alkene is CnH2n. - The physical properties of the members show a gradation in properties as the molecular mass increases.
- The chemical properties also show a gradient similarity.
Example: Methane and ethane react with chlorine to form methyl chloride and ethyl chloride, respectively.
CH4 + Cl2 → CH3Cl
C2H6 + Cl2 → C2H5Cl - All members of a homologous series can be prepared by the same general method of preparation.
Example: Alcohols can be prepared from alkyl halides.
`CH_3Br+KOH " Boil"/""CH_3OH+KBr`
`C_2H_5Br+KOH " Boil"/""C_2H_5OH+KBr`
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संबंधित प्रश्न
Write the name and formula of the 2nd member of homologous series having general formula CnH2n.
Write the name and formula of the 2nd member of homologous series having general formula CnH2n – 2.
Write the molecular formula of first two members of homologous series having functional group -Cl.
Complete the following table which relates to the homologous series of hydrocarbons.
|
General Formula |
IUPAC name of the homologous series | Characteristic bond type | IUPAC name of the first member of the series |
| `C_nH_(2n-2)` | (A)________ | (B)______ | (C)______ |
| C_nH_(2n+1) | (B)________ | (E)______ | (F)______ |
Define a homologous series. Give the name and structural formula of one homologue of the following:
CH3OH
What is a homologous series? Explain with an example.
Give the dot diagram of the first member of the alcohol.
Give the structure of the second member of the alcohol group.
What is homologous series ?
.
Complete the correlation:
Alkene : C = C :: Alkyne: _______.
Saturated hydrocarbon : Single bond : : Unsaturated hydrocarbon : _______
Write a short note.
Homologous series
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 |
The first member of alkyne homologous series is
Name the following organic compound:
The first homologue whose general formula is CnH2n.
Study and complete the following table:
| Homologous series | Alkane | Alkyne |
| General formula | CnH2n+2 | 1. ______ |
| IUPAC name | 2. ______ | Ethyne |
| Common name | Marsh gas | 3. ______ |
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?
Name the third homologue of alcohols.
