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ICSE Class 10 Chemistry Question 3 of 93

Organic Chemistry — Question 15

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15
Question

Question 15.1

Give equations for the conversions of – Methane, Ethane:

Methane toEthane to  
(a) Carbon tetrachloride(a) Hexachloro ethaneby - Substitution [diffused sunlight]
(b) Carbon dioxide(b) Carbon dioxideby - Oxidation - Complete
(c) Methanol
to
Methanal
to
Methanoic acid		Ethanol
to
Ethanal
to
Ethanoic acid		by - Oxidation
(i) catalytic using - catalyst copper [Cu]
(ii) Controlled using acidified K2Cr2O7
(d) MethnalEthanalby- Oxidation - Catalytic - using catalyst MoO
(e) EthyneEtheneby - Pyrolysis [dehydrogenation]
Answer

(a) Conversion of Methane to Carbon tetrachloride by substitution [diffused sunlight]:

CH4 methane+4Cl2→Δdiffused sunlightCCl4Carbon tetrachloride+4HCl\underset{\text{ methane} }{\text{CH}_4} + 4\text{Cl}_2 \xrightarrow[\Delta]{\text{diffused sunlight}} \underset{\text{Carbon tetrachloride}}{\text{CCl}_4} + 4\text{HCl}

(b) Conversion of Methane to Carbon dioxide by complete oxidation:

CH4 methane+2O2[excess]⟶CO2+2H2O+Δ\underset{\text{ methane} }{\text{CH}_4} + 2\text{O}_2\text{[excess]} \longrightarrow \text{CO}_2 + 2\text{H}_2\text{O} + \Delta

(c)(i) Conversion of Methane to Methanol to Methanal to Methanoic acid by catalytic oxidation using catalyst copper [Cu]:

2CH4 methane+O2→200°CCu tube2CH3OHmethanol2CH3OHmethanol+O2→catalystCu2HCHOmethanal+2H2O2HCHOmethanal+O2→catalystCu2H-COOHmethanoic acid\underset{\text{ methane}}{2\text{CH}_4} + \text{O}_2 \xrightarrow[200 \text{\degree C}]{\text{Cu tube}} \underset{\text{methanol}}{2\text{CH}_3\text{OH}} \\[1em] \underset{\text{methanol}}{2\text{CH}_3\text{OH}} + \text{O}_2 \xrightarrow[\text{catalyst}]{\text{Cu}} \underset{\text{methanal} }{\text{2HCHO}} + 2\text{H}_2\text{O} \\[1em] \underset{\text{methanal} }{\text{2HCHO}} + \text{O}_2 \xrightarrow[\text{catalyst}]{\text{Cu}} \underset{\text{methanoic acid} }{\text{2H-COOH}}

(c)(ii) Conversion of Methane to Methanol to Methanal to Methanoic acid by controlled slow oxidation using acidified K2Cr2O7:

CH4 Methane→K2Cr2O7[O]CH3OH methanol→K2Cr2O7[O]HCHO methanal→K2Cr2O7[O]HCOOHmethanoic acid\underset{\text{ Methane} }{\text{CH}_4} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text{ methanol}}{\text{CH}_3\text{OH}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text { methanal}}{\text{HCHO}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text{methanoic acid} }{\text{HCOOH}}

(d) Conversion of Methane to Methanal by catalytic oxidation using catalyst MoO:

CH4 methane+O2→350−500°CMoOHCHOmethanal+H2O\underset{\text{ methane}}{\text{CH}_4} + \text{O}_2 \xrightarrow[350 - 500 \text{\degree C}]{\text{MoO}} \underset{\text{methanal} }{\text{HCHO}} + \text{H}_2\text{O}

(e) Conversion of Methane to Ethyne by Pyrolysis [dehydrogenation]:

2CH4 methane→1500°CC2H2ethyne+3H2\underset{\text{ methane}}{2\text{CH}_4} \xrightarrow{1500 \degree \text{C}} \underset{\text{ethyne} }{\text{C}_2\text{H}_2} + 3\text{H}_2

(a) Conversion of Ethane to Hexachloro ethane by substitution [diffused sunlight]:

C2H6 ethane+Cl2→diffused sunlightΔC2H5Clmonochloroethane+HCl\underset{\text{ ethane} }{\text{C}_2\text{H}_6} + \text{Cl}_2 \underset{\Delta}{\xrightarrow{\text{diffused sunlight}}} \underset{\text{monochloroethane}}{\text{C}_2\text{H}_5\text{Cl}}+ \text{HCl}

C2H5Clmonochloroethane+Cl2[excess]⟶C2H4Cl2dichloroethane+HCl\underset{\text{monochloroethane} }{\text{C}_2\text{H}_5\text{Cl}} + \underset{\text{[excess]}}{\text{Cl}_2} \longrightarrow \underset{\text{dichloroethane}}{\text{C}_2\text{H}_4\text{Cl}_2}+ \text{HCl}

C2H4Cl2dichloroethane+Cl2⟶C2H3Cl3trichloroethane+HCl\underset{\text{dichloroethane}}{\text{C}_2\text{H}_4\text{Cl}_2} + \text{Cl}_2 \longrightarrow \underset{\text{trichloroethane}}{\text{C}_2\text{H}_3\text{Cl}_3}+ \text{HCl}

C2H3Cl3trichloroethane+Cl2⟶C2H2Cl4tetrachloroethane+HCl\underset{\text{trichloroethane}}{\text{C}_2\text{H}_3\text{Cl}_3} + \text{Cl}_2 \longrightarrow \underset{\text{tetrachloroethane}}{\text{C}_2\text{H}_2\text{Cl}_4}+ \text{HCl}

C2H2Cl4tetrachloroethane+Cl2⟶C2HCl5pentachloroethane+HCl\underset{\text{tetrachloroethane}}{\text{C}_2\text{H}_2\text{Cl}_4} + \text{Cl}_2 \longrightarrow \underset{\text{pentachloroethane}}{\text{C}_2\text{H}\text{Cl}_5}+ \text{HCl}

C2HCl5pentachloroethane+Cl2⟶C2Cl6hexachloroethane+HCl\underset{\text{pentachloroethane}}{\text{C}_2\text{H}\text{Cl}_5} + \text{Cl}_2 \longrightarrow \underset{\text{hexachloroethane}}{\text{C}_2\text{Cl}_6}+ \text{HCl}

(b) Conversion of Ethane to Carbon dioxide by complete oxidation:

2C2H6 ethane+7O2[excess]⟶4CO2+6H2O+Δ\underset{\text{ ethane}}{2\text{C}_2\text{H}_6} + 7\text{O}_2\text{[excess]} \longrightarrow \text{4CO}_2 + 6\text{H}_2\text{O} + \Delta

(c)(i) Conversion of Ethane to Ethanol to Ethanal to Ethanoic acid by catalytic oxidation using catalyst copper [Cu]:

2C2H6 ethane+O2→200°CCu tube2C2H5OHethanol2C2H5OHethanol+O2→catalystCu2CH3CHOethanal+2H2O2CH3CHOethanal+O2→catalystCu2CH3COOHethanoic acid\underset{\text{ ethane}}{2\text{C}_2\text{H}_6} + \text{O}_2 \xrightarrow[200 \text{\degree C}]{\text{Cu tube}} \underset{\text{ethanol}}{2\text{C}_2\text{H}_5\text{OH}} \\[1em] \underset{\text{ethanol}}{2\text{C}_2\text{H}_5\text{OH}} + \text{O}_2 \xrightarrow[\text{catalyst}]{\text{Cu}} \underset{\text{ethanal}}{2\text{CH}_3\text{CHO}} + 2\text{H}_2\text{O} \\[1em] \underset{\text{ethanal}}{2\text{CH}_3\text{CHO}} + \text{O}_2 \xrightarrow[\text{catalyst}]{\text{Cu}} \underset{ \text{ethanoic acid} }{2\text{CH}_3\text{COOH}}

(c)(ii) Conversion of Ethane to Ethanol to Ethanal to Ethanoic acid by controlled slow oxidation using acidified K2Cr2O7:

C2H6 Ethane→K2Cr2O7[O]C2H5OHethanol→K2Cr2O7[O]CH3CHOethanal→K2Cr2O7[O]CH3COOHethanoic acid\underset{\text{ Ethane} }{\text{C}_2\text{H}_6} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{ \text{ethanol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text{ethanal}}{\text{CH}_3\text{CHO}} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7]{\text{[O]}} \underset{\text{ethanoic acid}}{\text{CH}_3\text{COOH}}

(d) Conversion of Ethane to Ethanal by catalytic oxidation using catalyst MoO:

C2H6 ethane+O2→350−500°CMoOCH3CHOethanal+H2O\underset{\text{ ethane}}{\text{C}_2\text{H}_6} + \text{O}_2 \xrightarrow[350 - 500 \text{\degree C}]{\text{MoO}} \underset{\text{ethanal} }{\text{CH}_3\text{CHO}} + \text{H}_2\text{O}

(e) Conversion of Ethane to Ethene by Pyrolysis [dehydrogenation]:

C2H6 ethane→catalyst [Al2O3]500°CC2H4ethene+H2\underset{\text{ ethane}}{\text{C}_2\text{H}_6} \xrightarrow[\text{catalyst [Al}_2\text{O}_3\text{]}]{500 \degree \text{C}} \underset{\text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2