Alkanes - Conceptual Questions

1. What are hydrocarbons and How do you classify hydrocarbons?
2. What are alkanes and why they are called paraffins?
3. What is the general formual of cycloalkanes?
4. What is the general formual of open chain and acyclic alkanes?
5. What is the IUPAC system of nomenclature of alkanes?
6. What is the IUPAC system of nomenclature of cycloalkanes?
7. Explain the concept of conformations in alkanes.
8. Explain the saw horse representation and Newman representation of alkanes.
9. Discuss the stability of various conformations of alkanes.
10. Explain the concept of conformations in cycloalkanes.

11. Explain the following methods of preparation of alkanes.
i. From unsaturated hydrocarbons
ii. from alkyl halides
a. Wurtz reaction
b. Reduction of alkyl halides – using zinc and HCl, using hydrogen in presence of platinum or palladium (catalytic hydrogenation), using hydrogen iodide in presence of red phosphrus, using zinc copper couple and alcohol.
c. By reaction with Grignard reagent
iii. from carboxylic acids
a. Decarboxylation reaction
b. Kolbe’s reaction

12. What are physical properties of amines?
a. Physical state and smell
b. Melting point
c. Boiling points
d. Solubility in water
e. Density

13. Chemical Properties of Alkanes

A. Substitution reactions of alkanes
i. Halogenation
ii. Nitration
iii. Sulphonation

B. Oxidation
i. Complete oxidation or combustion
ii. Incomplete combustion
iii. controlled oxidation

C. Action of steam

D. Isomerisation (Formation of branched alkanes)
E. Aromatization
F. Thermal decomposition or fragmentation

Application Questions - 21 Alkanes

Past JEE Questions Ch.21 Alkanes

IIT JEE Chemistry Questions 21. Alkanes

Preparation, properties and reactions of alkanes:
Homologous series,
physical properties of alkanes (melting points, boiling points and density); Combustion and halogenation of alkanes;
Preparation of alkanes by Wurtz reaction and decarboxylation reactions.
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1. What happens to boiling point of alkanes as molecular mass increases?
2. What happens to boiling point of branched isomers of alkanes?
3. Under what conditions does monochlorination of methane take place?
4. What is the `reaction in Kolbe Electrolytic method of preparing alkanes?
5. What are the reactants and products in hydrolysis of Grignard reagent?
6. In the case of halogenation of alkanes, what is order of reactivity among chlorine, fluorine, and bromine?
7. At ordinary temperatures, why is ultraviolet radiation required to initiate a reaction between halogens and alkanes?
8. What do you understand by 1 degree H, 2 degree H and 3 degree H?
9. What is the difference in reactions between an alkane and fluorine and an alkane and bromine?
10. What is the major product in reaction between bromine and n-butane?
11. What are the products of reaction between n-butane and chlorine at room temperature and sunlight?
12. How do you get iso-butane from n-butane?
13. When do you get aromatic compounds from alkanes?
14. What is the more common name of Methane?
15. What is % composition of Methane in coal gas?
16. How do you produce methane from aluminium chloride?
17. What are the reactants and products of Wurtz reaction?



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