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ICSE Class 10 Chemistry Question 43 of 93

Organic Chemistry — Question 37

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Question

Question 5(2013)

Give balanced equations for the laboratory preparations of:

(i) A saturated hydrocarbon from iodomethane.

(ii) An unsaturated hydrocarbon from an alcohol.

(iii) An unsaturated hydrocarbon from calcium carbide.

(iv) An alcohol from ethyl bromide.

Answer

(i) Methane is produced

CH3I methyl iodide+2[H] nascent hydrogen→Zn/Cu couplealcoholCH4 methane+HI\underset{\text{ methyl iodide}}{\text{CH}_3\text{I}} + \underset{ \text{ nascent hydrogen}}{2\text{[H]}} \underset{\text{alcohol}}{\xrightarrow{\text{Zn/Cu couple}}} \underset{ \text{ methane}}{\text{CH}_4} + \text{HI}

(ii) Ethene is formed

C2H5OH ethyl alcohol→170°CConc. H2SO4[excess]C2H4ethene+H2O \underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170\degree\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2\text{O}\

(iii) Ethyne is formed

CaC2calcium carbide+2H2Owater⟶C2H2ethyne [acetylene]+Ca(OH)2\underset{\text{calcium carbide}}{\text{CaC}_2} + \underset{\text{water}}{2\text{H}_2\text{O}} \longrightarrow \underset{\text{ethyne [acetylene]}}{\text{C}_2\text{H}_2} + \text{Ca(OH)}_2

(iv) ethyl alcohol is formed.

C2H5-Br Bromoethane [ethyl bromide]+KOH [aq.] alcoholic KOH→boilC2H5OH ethyl alcohol+KBr\underset{\text{ Bromoethane [ethyl bromide]}}{\text{C}_2\text{H}_5\text{-Br}} + \underset{\text{ alcoholic KOH}}{\text{KOH [aq.]}} \xrightarrow{\text{boil}} \underset{ \text{ ethyl alcohol}} {\text{C}_2\text{H}_5\text{OH}} + \text{KBr}