Draw the branched structural formula of the following organic compounds whose IUPAC names are given below.
Pent-1-ene But-2-yne 3-methyl pentane 2-methyl-prop-1-ene Pentan-3-ol 1, 1, 2, 2 tetrabromoethane 2-methyl butan-2-ol 2, 2 dimethylpropan-1-ol 2, 2 dimethyl propane 2-bromo-4-chloro pentane Answer
Pent-1-ene
But-2-yne
3-methyl pentane
2-methyl-prop-1-ene
Pentan-3-ol
1, 1, 2, 2 tetrabromoethane
2-methyl butan-2-ol
2, 2 dimethylpropan-1-ol
2, 2 dimethyl propane
2-bromo-4-chloro pentane
Select the correct answer from the choice in brackets.
The vapour density of the fifth member of the homologous series of alkanes. [22/36/29] The isomer of pentane which has '1' C atom attached to '4' other C atoms [n-/iso-/neo-] pentane. The IUPAC name of the product of reaction of ethylene with hydrogen bromide, [ethyl bromide/bromoethane/dibromoethane] The IUPAC name of methyl acetylene. [1-butyne/propyne/ethyne] The functional group in ethanoic acid. [aldehydic/carboxyl/hydroxyl] Answer
36 neo-pentane bromoethane propyne carboxyl Give balanced equations for the following conversions:
1,2 dibromoethane → A Acetylene → B Silver acetylide \text{1,2 dibromoethane} \xrightarrow{\text{A}} \text{Acetylene} \xrightarrow{\text{B}} \text{Silver acetylide} 1,2 dibromoethane A Acetylene B Silver acetylide Ethanol → C Ethene ← D Ethyl iodide \text{Ethanol} \xrightarrow{\text{C}} \text{Ethene} \xleftarrow{\text{D}} \text{Ethyl iodide} Ethanol C Ethene D Ethyl iodide Bromoethane → E Ethane ← F Sodium propanoate \text{Bromoethane} \xrightarrow{\text{E}} \text{Ethane} \xleftarrow{\text{F}} \text{Sodium propanoate} Bromoethane E Ethane F Sodium propanoate Sodium ethanoate → G Marsh gas → G 1 Methanol → G 2 Methanal → G 3 Methanoic acid \text{Sodium ethanoate} \xrightarrow{\text{G}} \text{Marsh gas} \xrightarrow{\text{G}_1} \text{Methanol} \xrightarrow{\text{G}_2} \text{Methanal} \xrightarrow{\text{G}_3} \text{Methanoic acid} Sodium ethanoate G Marsh gas G 1 Methanol G 2 Methanal G 3 Methanoic acid Sodium acetate + H 2 ← H Acetic acid → H 1 Ethyl ethanoate \text{Sodium acetate + H}_2 \xleftarrow{\text{H}} \text{Acetic acid} \xrightarrow{\text{H}_1} \text{Ethyl ethanoate} Sodium acetate + H 2 H Acetic acid H 1 Ethyl ethanoate Answer
1. 1,2 dibromoethane → A Acetylene \text{1,2 dibromoethane} \xrightarrow{\text{A}} \text{Acetylene} 1,2 dibromoethane A Acetylene
Acetylene → B Silver acetylide \text{Acetylene} \xrightarrow{\text{B}} \text{Silver acetylide} Acetylene B Silver acetylide
HC ≡ CH ethyne + 2 AgNO 3 + 2 NH 4 OH ⟶ Ag-C ≡ C-Ag Silver Acetylide + 2 NH 4 NO 3 + 2 H 2 O \underset{\text{ ethyne}}{\text{HC ≡ CH}} + 2\text{AgNO}_3 + 2\text{NH}_4\text{OH} \longrightarrow \underset{\text{Silver Acetylide}}{\text{Ag-C ≡ C-Ag}} + 2\text{NH}_4\text{NO}_3 + 2\text{H}_2\text{O} ethyne HC ≡ CH + 2 AgNO 3 + 2 NH 4 OH ⟶ Silver Acetylide Ag-C ≡ C-Ag + 2 NH 4 NO 3 + 2 H 2 O
2. Ethanol → C Ethene \text{Ethanol} \xrightarrow{\text{C}} \text{Ethene} Ethanol C Ethene
C 2 H 5 OH ethyl alcohol → 170 ° C Conc. H 2 SO 4 [excess] C 2 H 4 ethene + H 2 O \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}\ ethyl alcohol C 2 H 5 OH Conc. H 2 SO 4 [excess] 170° C ethene C 2 H 4 + H 2 O
Ethyl iodide → D Ethene \text{Ethyl iodide} \xrightarrow{\text{D}} \text{Ethene} Ethyl iodide D Ethene
C 2 H 5 I ethyl iodide + KOH alcoholic → boil C 2 H 4 ethene + KI + H 2 O \underset{\text{ ethyl iodide}}{\text{C}_2\text{H}_5\text{I}} + \underset{ \text{ alcoholic}}{\text{KOH}} {\xrightarrow{\text{boil}}} \underset{ \text{ ethene}}{\text{C}_2\text{H}_4} + \text{KI} +\text{H}_2\text{O} ethyl iodide C 2 H 5 I + alcoholic KOH boil ethene C 2 H 4 + KI + H 2 O
3. Bromoethane → E Ethane \text{Bromoethane} \xrightarrow{\text{E}} \text{Ethane} Bromoethane E Ethane
C 2 H 5 Br bromoethane + 2 [H] nascent hydrogen → alcohol Zn/Cu couple C 2 H 6 ethane + HBr \underset{\text{bromoethane}}{\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} bromoethane C 2 H 5 Br + nascent hydrogen 2 [H] Zn/Cu couple alcohol ethane C 2 H 6 + HBr
Ethane ← F Sodium propanoate \text{Ethane} \xleftarrow{\text{F}} \text{Sodium propanoate} Ethane F Sodium propanoate
C 2 H 5 COONa sodium propanoate + NaOH sodalime → 300 ° C CaO C 2 H 6 ↑ ethane + Na 2 CO 3 \underset{\text{sodium propanoate}}{\text{C}_2\text{H}_5\text{COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \xrightarrow[300\degree\text{C}]{\text{CaO}} \underset{\text{ethane}}{\text{C}_2\text{H}_6 \uparrow} + \text{Na}_2\text{CO}_3 sodium propanoate C 2 H 5 COONa + sodalime NaOH CaO 300° C ethane C 2 H 6 ↑ + Na 2 CO 3
4. Sodium ethanoate → G Marsh gas \text{Sodium ethanoate} \xrightarrow{\text{G}} \text{Marsh gas} Sodium ethanoate G Marsh gas
CH 3 COONa sodium acetate + NaOH sodalime → 300 ° C CaO C H 4 ↑ methane + Na 2 CO 3 \underset{\text{ sodium acetate}}{\text{CH}_3\text{COONa}} + \underset{\text{sodalime}}{\text{NaOH}} \xrightarrow[300\degree\text{C}]{\text{CaO}} \underset{\text{methane}}{\text{C}\text{H}_4 \uparrow} + \text{Na}_2\text{CO}_3 sodium acetate CH 3 COONa + sodalime NaOH CaO 300° C methane C H 4 ↑ + Na 2 CO 3
Methane to Methanol to Methanal to Methanoic acid
CH 4 Methane → K 2 Cr 2 O 7 [O] CH 3 OH methanol → K 2 Cr 2 O 7 [O] HCHO methanal → K 2 Cr 2 O 7 [O] HCOOH methanoic 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}} Methane CH 4 [O] K 2 Cr 2 O 7 methanol CH 3 OH [O] K 2 Cr 2 O 7 methanal HCHO [O] K 2 Cr 2 O 7 methanoic acid HCOOH
5. Sodium acetate + H 2 ← H Acetic acid \text{Sodium acetate + H}_2 \xleftarrow{\text{H}} \text{Acetic acid} Sodium acetate + H 2 H Acetic acid
2 CH 3 COOH Acetic acid + 2 Na ⟶ 2 CH 3 COONa sodium acetate + H 2 2\underset{\text{Acetic acid}}{\text{CH}_3\text{COOH}} + 2\text{Na} \longrightarrow \underset{\text{sodium acetate}}{2\text{CH}_3\text{COONa}} + \text{H}_2 2 Acetic acid CH 3 COOH + 2 Na ⟶ sodium acetate 2 CH 3 COONa + H 2
Acetic acid → H 1 Ethyl ethanoate \text{Acetic acid}\xrightarrow{\text{H}_1} \text{Ethyl ethanoate} Acetic acid H 1 Ethyl ethanoate
C 2 H 5 OH ethyl alcohol + CH 3 COOH Acetic acid → Conc. H 2 SO 4 CH 3 − COO − C 2 H 5 ethyl ethanoate + H 2 O \underset{\text{ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{Acetic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{ethyl ethanoate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O} ethyl alcohol C 2 H 5 OH + Acetic acid CH 3 COOH Conc. H 2 SO 4 ethyl ethanoate CH 3 − COO − C 2 H 5 + H 2 O
Select from the letters A to G the correct answer corresponding to the statements from 1 to 5 :
A : Ammoniacal CuCl2 B : TrichloromethaneC : TrichloroethaneD : Bromine soln.E : Aqueous KOHF : EtheneG : SodalimeH : EthanolI : Ethyne
The organic compound which forms carbon tetrachloride on reaction with chlorine. The reagent which can distinguish between ethene and ethyne. The substance which reacts with bromoethane to give ethanol. The substance which gives bromoethane on reaction with hydrogen bromide. The substance which reacts with acetic acid to give CH3 COOC2 H5 Answer
The organic compound which forms carbon tetrachloride on reaction with chlorine. — B : Trichloromethane The reagent which can distinguish between ethene and ethyne. — A : Ammoniacal CuCl2 The substance which reacts with bromoethane to give ethanol. — E : Aqueous KOH The substance which gives bromoethane on reaction with hydrogen bromide. — F : Ethene The substance which reacts with acetic acid to give CH3 COOC2 H5 — H : Ethanol Give balanced equations for the following conversions.
An alkyne to an alkene. An alkene to an alkane. An alkane to an alcohol. An alcohol to an alkene. A carboxylic acid to an ammonium salt Answer
1. An alkyne to an alkene:
H 2 C 2 ethyne [acetylene] + H 2 → 300 ° C Nickle C 2 H 4 ethene \underset{\text{ ethyne [acetylene]}}{\text{H}_2\text{C}_2} + \text{H}_2 \xrightarrow[300\degree\text{C}]{\text{Nickle}} \underset{\text{ethene}}{\text{C}_2\text{H}_4} ethyne [acetylene] H 2 C 2 + H 2 Nickle 300° C ethene C 2 H 4
2. An alkene to an alkane:
C 2 H 4 ethene + H 2 → 300 ° C Nickle C 2 H 6 ethane \underset{\text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2 \xrightarrow[300\degree\text{C}]{\text{Nickle}} \underset{\text{ethane}}{\text{C}_2\text{H}_6} ethene C 2 H 4 + H 2 Nickle 300° C ethane C 2 H 6
3. An alkane to an alcohol:
2 C 2 H 6 ethane + O 2 → 200 °C Cu tube 2 C 2 H 5 OH ethanol \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}} ethane 2 C 2 H 6 + O 2 Cu tube 200 °C ethanol 2 C 2 H 5 OH
4. An alcohol to an alkene:
C 2 H 5 OH ethyl alcohol → 170 ° C Conc. H 2 SO 4 [excess] C 2 H 4 ethene + H 2 O \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}\ ethyl alcohol C 2 H 5 OH Conc. H 2 SO 4 [excess] 170° C ethene C 2 H 4 + H 2 O
5. A carboxylic acid to an ammonium salt :
CH 3 COOH acetic acid + NH 4 OH ⟶ CH 3 COONH 4 Ammonium acetate + H 2 O \underset{\text{ acetic acid}}{\text{CH}_3\text{COOH}} + \text{NH}_4\text{OH}\longrightarrow \underset{ \text{Ammonium acetate}}{\text{CH}_3\text{COONH}_4} + \text{H}_2\text{O}\ acetic acid CH 3 COOH + NH 4 OH ⟶ Ammonium acetate CH 3 COONH 4 + H 2 O
Give reasons for the following :
Concentrated sulphuric acid may be added during esterification of acetic acid.
Answer
Reversible reaction may be prevented by using conc. H2 SO4 when the reaction is about to complete by removing H2 O.
C 2 H 5 OH ethyl alcohol + CH 3 COOH acetic acid → Conc. H 2 SO 4 CH 3 − COO − C 2 H 5 ethyl ethanoate + H 2 O \underset{\text{ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} + \underset{\text{acetic acid}}{\text{CH}_3\text{COOH}} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \underset{\text{ethyl ethanoate}}{\text{CH}_3-\text{COO}-\text{C}_2\text{H}_5} + \text{H}_2\text{O} ethyl alcohol C 2 H 5 OH + acetic acid CH 3 COOH Conc. H 2 SO 4 ethyl ethanoate CH 3 − COO − C 2 H 5 + H 2 O
Give reasons for the following :
Isomers belonging to the same homologous series may differ in physical properties but not in chemical properties.
Answer
As isomers have same general molecular formula and functional group (if any) and only differ in structural formula, hence, they show same chemical properties and differ in physical properties.
Give reasons for the following :
A given organic compound can be assigned only one name on the basis of the IUPAC system.
Answer
IUPAC is a systematic way of nomenclature of organic compounds that takes into account only one molecular structure of the compound. Hence, it assigns only one name to the compound.
Give reasons for the following :
Substitution reactions are characteristic reactions of saturated organic compounds only.
Answer
In saturated hydrocarbons, all the four valencies of each carbon are satisfied by the hydrogen atoms, forming single covalent bond. The non-availability of electrons in the single covalent bond makes them less reactive and therefore undergo characteristic substitution reaction only. Addition reactions are not possible in case of saturated organic compounds.
Give reasons for the following :
Acetic acid is considered an aliphatic monocarboxylic acid.
Answer
Acetic acid (CH3 – COOH) contains only one – COOH group (carboxylic acid group) that is why it is called a monocarboxylic acid. As acetic acid does not contain a benzene ring, so it is an aliphatic monocarboxylic acid.
