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ICSE Class 10 Chemistry Question 2 of 93

Organic Chemistry — Question 14

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Question 14

Give balanced equations for the laboratory preparations of - Alkanes, Alkenes, Alkynes, Alcohols and Acids.

Sl.
No.		Compoundfrom:by/from:
(a)Methane [CH4]Sodium ethanoate [sodium acetate]by -decarboxylation
(b)Methane [CH4]Iodo methane [methyl iodide]from -an alkylhalide
(c)Ethane [C2H6]Sodium propanoate [sodium propionate]by -decarboxylation
(d)Ethane [C2H6]Bromo ethane [ethyl bromide]from -alkylhalide
(e)Ethene [C2H4]from ethanol [ethyl alcohol]by -dehydration
(f)Ethene [C2H4]Bromo ethane [ethyl bromide]by - dehydrohalogenation
(g)Ethyne [C2H2]from calcium carbidefrom -a calcium compound
(h)Ethyne [C2H2]1,2, dibromoethane [ethylene dibromide]by -dehydrohalogenation
(i)Ethanol [C2H5OH]Bromo ethane [ethyl bromide]by - hydrolysis of alkylhalide
(j)Ethanol [C2H5OH]Ethene [ethylene]by - hydration of ethene
(k)Ethanoic acid [CH3COOH]Ethanol [ethyl alcohol]by - oxidation of alcohol
Answer

(a) Methane [CH4] by decarboxylation :

CH3.COONa sodium acetate+NaOHsodalime→ΔCaOCH4methane+Na2CO3\underset{\text{ sodium acetate}}{\text{CH}_3\text{.COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \xrightarrow[\Delta]{\text{CaO}} \underset{\text{methane}}{\text{C}\text{H}_4} + \text{Na}_2\text{CO}_3

(b) Methane [CH4] from alkyl halide :

CH3I methyl iodide+2[H] nascent hydrogen→alcoholZn/Cu coupleCH4 methane+HI\underset{\text{ methyl iodide}}{\text{CH}_3\text{I}} + \underset{ \text{ nascent hydrogen}}{2\text{[H]}} \xrightarrow[\text{alcohol}]{\text{Zn/Cu couple}} \underset{ \text{ methane}}{\text{CH}_4} + \text{HI}

(c) Ethane [C2H6] by decarboxylation :

C2H5COONasodium propionate+NaOHsodalime→ΔCaOC2H6ethane+Na2CO3\underset{\text{sodium propionate}}{\text{C}_2\text{H}_5\text{COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \xrightarrow[\Delta]{\text{CaO}} \underset{\text{ethane}}{\text{C}_2\text{H}_6} + \text{Na}_2\text{CO}_3

(d) Ethane [C2H6] from alkylhalide :

C2H5Brethylbromide+2[H]nascent hydrogen→alcoholZn/Cu coupleC2H6ethane+HBr\underset{\text{ethylbromide}}{\text{C}_2\text{H}_5\text{Br}} + \underset{\text{nascent hydrogen}}{2\text{[H]}} \xrightarrow[\text{alcohol}]{\text{Zn/Cu couple}} \underset{\text{ethane}}{\text{C}_2\text{H}_6} +\text{HBr}

(e) Ethene [C2H4] by dehydration :

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}\

(f) Ethene [C2H4] by dehydrohalogenation :

C2H5-Br Bromoethane+KOHalcoholic→boilC2H4 ethene+KBr+H2O\underset{\text{ Bromoethane}}{\text{C}_2\text{H}_5\text{-Br}} + \underset{\text{alcoholic}}{\text{KOH}} \xrightarrow{\text{boil}} \underset{ \text{ ethene} } {\text{C}_2\text{H}_4} + \text{KBr} + \text{H}_2\text{O}

(g) Ethyne [C2H2] from Calcium Carbide :

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

(h) Ethyne [C2H2] from 1,2, dibromoethane [ethylene dibromide] by -dehydrohalogenation :

Write balanced chemical equation for the reaction between 1, 2 – dibromoethane and alcoholic potassium hydroxide. Organic Chemistry, Simplified Chemistry Dalal Solutions ICSE Class 10

(i) Ethanol [C2H5OH] by hydrolysis of alkylhalide:

C2H5-Br Bromo Ethane+KOHaqueous→boilC2H5OH ethanol+KBr\underset{\text{ Bromo Ethane}}{\text{C}_2\text{H}_5\text{-Br}} + \underset{\text{aqueous}}{\text{KOH}} \xrightarrow{\text{boil}} \underset{ \text{ ethanol}} {\text{C}_2\text{H}_5\text{OH}} + \text{KBr}

(j) Ethanol [C2H5OH] by hydration of ethene:

C2H4Ethene+H2SO4[conc.]→30 atmos.80°CC2H5-HSO4Ethyl hydrogen sulphate\underset{\text{Ethene}}{\text{C}_2\text{H}_4} + \underset{\text{[conc.]}}{\text{H}_2\text{SO}_4} \xrightarrow[30 \text{ atmos.}]{80\degree \text{C}} \underset{\text{Ethyl hydrogen sulphate}}{\text{C}_2\text{H}_5\text{-HSO}_4}

C2H5-HSO4Ethyl hydrogen sulphate+H2O[steam]⟶C2H5OH ethanol+H2SO4\underset{\text{Ethyl hydrogen sulphate}}{\text{C}_2\text{H}_5\text{-HSO}_4} + \underset{\text{[steam]}}{\text{H}_2\text{O}} \longrightarrow \underset{\text{ ethanol} }{\text{C}_2\text{H}_5\text{OH}} + \text{H}_2\text{SO}_4

[C2H4Ethene+H2O steam→acidH+C2H5OH ethanol]\bigg[\underset{\text{Ethene}}{\text{C}_2\text{H}_4} + \underset{\text{ steam} }{\text{H}_2\text{O}} \xrightarrow[\text{acid}]{\text{H}^\text{+}} \underset{\text{ ethanol} }{\text{C}_2\text{H}_5\text{OH}}\bigg]

(k) Ethanoic acid [CH3COOH] by oxidation of alcohol :

C2H5OH Ethanol+[O]→acidifiedK2Cr2O7CH3CHO[Acetaldehyde]+H2O\underset{\text{ Ethanol}}{\text{C}_2\text{H}_5\text{OH}} +[\text{O}]\xrightarrow[\text{acidified}]{\text{K}_2\text{Cr}_2\text{O}_7} \underset{\text{[Acetaldehyde]} }{\text{CH}_3\text{CHO}} + \text{H}_2\text{O}

CH3CHO[Acetaldehyde]+[O]→acidifiedK2Cr2O7CH3COOH[Acetic acid]\underset{\text{[Acetaldehyde]} }{\text{CH}_3\text{CHO}} +[\text{O}]\xrightarrow[\text{acidified}]{\text{K}_2\text{Cr}_2\text{O}_7} \underset{\text{[Acetic acid]} }{\text{CH}_3\text{COOH}}