CBSE Class 10 Science Carbon and its compounds Assignment Set 08

Question. Give the structural formulae of:
(1) 2-methyl propane
(2) Ethanoic acid
(3) Butan – 2 – ol
Answer:
(1) 2-Methyl propane:

    H   H   H
    |   |   |
H - C - C - C - H
    |   |   |
    H   C   H
        |
        H

(2) Ethanoic acid:

    H   O
    |   ||
H - C - C - O - H
    |
    H

(3) Butan – 2 – ol:

    H   H   OH  H
    |   |   |   |
H - C - C - C - C - H
    |   |   |   |
    H   H   H   H

Question. Compound A is bubbled through bromine dissolved in carbon tetrachloride is as follows:
\( \text{A} \xrightarrow{\text{Br}_2 / \text{CCl}_4} \text{CH}_2\text{Br} - \text{CH}_2\text{Br} \)

(1) Draw the structure of A.
(2) State your observation during this reaction.
Answer:
(1) Structure of A (Ethene):

    H   H
    |   |
H - C = C - H

Reaction:
\( \text{CH}_2=\text{CH}_2 + \text{Br}_2 \xrightarrow{\text{CCl}_4} \text{CH}_2(\text{Br}) - \text{CH}_2(\text{Br}) \)
(Orangish red) → (1, 2 dibromo ethane, colourless)

(2) Bromine water turns colourless.

Question. Fill in the blanks from the choices given in brackets – The compound formed when ethene reacts with hydrogen is……….. [CH4, C2H6, C3H8]
Answer: The compound formed when ethene reacts with hydrogen is \( \text{C}_2\text{H}_6 \).

Question. Choose the correct answer from the options given – If the molecular formula of an organic compound is \( \text{C}_{10}\text{H}_{18} \) it is –
(a) Alkene
(b) Alkane
(c) Alkyne
(d) Not a hydrocarbon
Answer: (c) Alkyne

Question. Identify the substance underlined – An organic compound containing – COOH functional group.
Answer: Ethanoic acid \( [\text{CH}_3\text{—COOH}] \)

Question. Write the balanced chemical equation for – Preparation of methane from iodomethane
Answer: \( \text{CH}_3\text{I} + 2[\text{H}] \xrightarrow{\text{Zn/Cu couple}} \text{CH}_4 + \text{HI} \)

Question. Identify the term or substance based on the descriptions given below:
1. Ice like crystals formed on cooling an organic acid sufficiently.
2. Hydrocarbon containing a triple bond used for welding purpose.
3. The property by virtue of which the compound has the same molecular formula but different structural formulae.
4. The compound formed where two alkyl groups are linked by \( \text{>C=O} \) group.
Answer:
1. Glacial acetic acid
2. Ethyne or acetylene
3. Isomerism
4. Ketone or Alkanone

Question. Give a balanced chemical equation for each of the following –
1. Preparation of ethane from sodium propionate.
2. Action of alcoholic KOH on bromoethane.
Answer:
1. \( \text{C}_2\text{H}_5\text{COONa} + \text{NaOH} \rightarrow \text{C}_2\text{H}_6 + \text{Na}_2\text{CO}_3 \)
2. \( \text{CH}_3\text{Br} + \text{KOH} \rightarrow \text{CH}_3\text{OH} + \text{KBr} \)

Question. State one relevant observation for the following reaction – Addition of ethyl alcohol to acetic acid in the presence of concentrated sulphuric acid.
Answer: On warming the mixture gives fruity smell.

Question. Draw the structure formula for each of the following –
1. 2, 3 – dimethyl butane
2. Diethyl ether
3. Propanoic acid
Answer:
1. 2, 3 – dimethyl butane:

    H  CH3 CH3  H
    |   |   |   |
H - C - C - C - C - H
    |   |   |   |
    H   H   H   H

2. Diethyl ether:

    H   H       H   H
    |   |       |   |
H - C - C - O - C - C - H
    |   |       |   |
    H   H       H   H

3. Propanoic acid:

    H   H   O
    |   |   ||
H - C - C - C - OH
    |   |
    H   H

ADDITIONAL QUESTIONS

Question. Explain the term ‘Organic Chemistry’. State the ‘Natural sources’ and ‘Importance’ of organic compounds.
Answer:
1. Organic Chemistry - It is the chemistry of specific carbon compounds except – oxides, carbonates, bicarbonates and metallic carbides.
2. Plants, Animals, Petroleum, dyes and drugs are all natural sources.
3. Compounds of organic origin are : Food – carbohydrates, vitamins; Dyes – azodyes; Clothing – cotton, silk and wool; Fuels – petrol; Medicines – penicillin; Explosives – trinitrotoluene.

Question. Explain the ‘unique nature of carbon atom’ with specific reference and meaning to —
(a) ‘Tetravalency’ — leading to formation of single, double and triple bonds
(b) ‘Catenation’ — leading to formation of straight chain, branch chain and cyclic compounds.
Answer:
Some unique properties shown by carbon atom are :
(a) Tetravalency
(b) Catenation
(c) Ability to form multiple bonds.

(a) Tetravalency: Atomic number of carbon is 6. Its electronic configuration is 2, 4. Therefore, it has four electrons in its valence shell. Carbon atom can neither lose nor gain electrons to complete its octet (not possible from energy point of view). Therefore, carbon atom completes its octet by sharing four electrons with other atoms, i.e., it can form four covalent bonds, called its tetracovalency.
For example:
Methane, \( \text{CH}_4 \):

    H
    |
H - C - H
    |
    H

Ethene, \( \text{C}_2\text{H}_4 \):

    H   H
    |   |
H - C = C - H

(b) Catenation: The property by virtue of which a large number of atoms of the same element get linked together through single or multiple covalent bonds, forming straight or branched chains and rings of different sizes, is called catenation. Carbon shows catenation to the maximum extent due to strong carbon-carbon bonds and its tetracovalency.
In this process of catenation, carbon atoms form straight or branched chains and cyclic rings of various sizes and can involve single, double or triple covalent bonds.

Question. State reasons for ‘Justification of a separate branch’ for ‘Organic Chemistry’.
Answer:
This is due to the following reasons:
1. The number of known organic compounds is very large as compared to the number of known inorganic compounds.
2. Organic compounds involve only a few elements (C, H, O, N, S, P, F, Cl, Br, I etc.), whereas inorganic compounds involve all the known elements.
3. Organic compounds have complex nature and have high molecular mass.
4. Organic compounds involve covalent bonds whereas inorganic compounds involve electrovalent bonds.
5. Organic compounds show isomerism whereas inorganic compounds do not show isomerism.
6. The properties of organic compounds are different from inorganic compounds.
All these facts convince us to study organic chemistry as a separate branch of chemistry.

Question. State five differences between the characteristics of organic and inorganic compounds. State how organic compounds are classified.
Answer:
(a) Characteristics of organic compounds :
1. These are made up of only a few elements C, H, O, N, S, X(Cl, Br, I)
2. These involve covalent bonds.
3. These are generally gases or liquids
4. They have low melting and boiling points.
5. They are combustible.
6. They show molecular reactions.
7. They show isomerism.
8. These are non-conductors of electricity.
9. They are generally insoluble in water but soluble in organic solvents.

Characteristics of inorganic compounds :
1. These are made up of all the known elements.
2. These involve ionic bonds.
3. These are generally solids.
4. They have high melting and boiling points.
5. They are non-combustible.
6. They show ionic reactions.
7. They don’t show isomerism.
8. These are generally good conductors of electricity.
9. These are generally soluble in water but insoluble in organic solvents.

(b) Classification of Organic Compounds:
Aliphatic – Open Chain Compounds:
Hydrocarbons [Compounds containing carbon and hydrogen only]
- Saturated: Alkanes (Methane, Ethane [\( \text{C}_2\text{H}_6 \)])
- Unsaturated: Alkenes (Ethene [\( \text{C}_2\text{H}_4 \)]), Alkynes (Ethyne [\( \text{C}_2\text{H}_2 \)])

Cyclic – Closed Chain Compounds:
- Homocyclic (only C atoms): Aromatic e.g., Benzene
- Heterocyclic (C, O, N, S atoms): Aromatic e.g., Pyridine

Question. Explain the term ‘Homologous series’. State the general characteristics of members of the series with special reference to molecular mass or molecular formula.
Answer:
Homologous series is a series of organic compounds, that are grouped into a smaller number of series of compound.
General Characteristics of homologous series :
1. The members of a series have same functional group.
2. Two consecutive members of a homologous series differs each other in their composition by \( -\text{CH}_2 \) unit.
Example : Alcohol (-OH)
\( \text{CH}_3 – \text{OH} \), \( \text{CH}_3 – \text{CH}_2 – \text{OH} \), \( \text{CH}_3 – \text{CH}_2 – \text{CH}_2 – \text{OH} \)
3. The members of a homologous series can be represented by same general formula.
Example :
Alcohol — \( \text{C}_n\text{H}_{2n+1}\text{OH} \)
Aldehyde — \( \text{C}_n\text{H}_{2n+1}\text{CHO} \)
Carboxylic acid — \( \text{C}_n\text{H}_{2n+1}\text{COOH} \)
4. The members of a particular homologous series have almost same chemical properties due to presence of same functional group.
5. The physical properties (like solubility, melting point, boiling point, state) of members of a homologous series either gradually increase or decrease with increase in molecular mass.
6. The members of a homologous series can be prepared by same or common general method of preparation.
7. The first member of homologous series generally shows certain different chemical behavior than other members of the series.

Question. Differentiate between — ‘Molecular formula’ and ‘Structural formula’ — of an organic compound. Write the ‘condensed structural formula and ‘branched structural formula’ of ethene.
Answer:
Molecular formula: It shows all the atoms in a molecule or formula unit.
Structural formula: It shows the actual arrangement of atoms in a molecule.

The ‘condensed structural formula’ and ‘branched structural formula’ of ethene:
- Molecular formula: \( \text{C}_2\text{H}_4 \)
- Condensed Structural formula: \( \text{C}_2\text{H}_4 \) (\( \text{H}_2\text{C} = \text{CH}_2 \))
- Branched Structural formula:

  H     H
   \   /
    C=C
   /   \
  H     H

Question. State what are ‘Alkyl groups’. State the alkyl group of the parent alkane — methane and ethane.
Answer:
Alkyl Group: It is obtained by removing one hydrogen atom from a molecule of an alkane.
Methane: Methyl (Alkyl group)
Ethane: Ethyl (Alkyl group)

Question. State what are ‘Functional groups’. Name the following functional groups — \( \text{C}=\text{C} \); \( \text{–C}\equiv\text{C–} \); \( \text{–OH} \); \( \text{–CHO} \); \( \text{–COOH} \); \( \text{X} = \text{–F}, \text{–Cl}, \text{–Br}, \text{–I} \); \( \text{–C}=\text{O} \); \( \text{–C–O–C–} \)
Answer:
Functional Groups: An atom, radical or bond which defines the structure of an organic compound and give it its characteristic properties.

Question. Explain the terms — ‘Isomers’ and ‘Isomerism’. State the ‘Characteristics of isomers’ with reference to — Properties of isomers; Number of isomers with relation to carbon atoms in the isomer. Differentiate between — ‘Chain isomerism’ and ‘Position isomerism’ – with suitable examples.
Answer:
Two or more compounds having the same molecular formula but different physical and chemical properties are called isomers and this phenomenon is known as isomerism.

Isomers have the same number of atoms of each element in them and the same atomic weight but differ in other properties. For example, there are two compounds with the molecular formula \( \text{C}_2\text{H}_6\text{O} \). One is ethanol (ethyl alcohol), \( \text{CH}_3\text{CH}_2\text{OH} \), a colorless liquid alcohol; the other is dimethyl ether, \( \text{CH}_3\text{OCH}_3 \), a colorless gaseous ether.

Alkanes with more than three carbon atoms form isomers. The various isomers differ in the framework of the carbon chains.

Differentiate between — ‘Chain isomerism’ and ‘Position isomerism’

Chain isomers: Compounds having same molecular formula with difference in carbon chain pattern like linear or branch are called chain isomers. 1-Pentyne is chain isomer for 3-methyl Butyne.
\( \text{CH}_3 – \text{CH}_2 – \text{CH}_2 – \text{C} \equiv \text{CH} \) and \( \text{CH}_3 – \text{CH(CH}_3\text{)} – \text{C} \equiv \text{CH} \)

Position isomers: Compounds having same molecular formula with difference in position of the functional group are called position isomers. 1-Butyne and 2-Butyne are position isomers.
\( \text{CH}_3 – \text{CH}_2 – \text{C} \equiv \text{CH} \) and \( \text{CH}_3 – \text{C} \equiv \text{C} – \text{CH}_3 \).

Question. Explain the term – ‘Nomenclature’. State its need with reference to organic compounds. State the basic rules of Nomenclature by the trivial system – with suitable examples. Explain the longest chain rule and the smallest number for functional groups rule of Nomenclature by the IUPAC system – with suitable examples.
Answer:
(a) Nomenclature :
Nomenclature is the system of assignment of names to organic compounds.
Need for Nomenclature : Very large number of organic compounds with varying molecular structure need a systematic method of nomenclature. Further many a times same molecular formula represents two or more compounds (isomerism).

(b) Nomenclature by Trivial System:
In this method, name of an organic compound is derived from its:
1. Source (e.g., benzoic acid is obtained by distillation from gum benzoin, fructose or fruit sugar from fruits etc).
2. Latin or Greek origin (e.g., formic acid, \( \text{HCOOH} \) is present in sting of red ants, formicus in Latin means an ant).
3. Properties (e.g., palmitic acid is an acid derived from palm oil etc).

(c) Longest Chain Rule :
1. In the nomenclature of alkanes, the longest continuous chain of C-atoms is selected. For this, alkyl groups, if present, are written in the expanded form.
For example:
\( \text{CH}_3 - \text{CH(C}_2\text{H}_5) - \text{CH(C}_2\text{H}_5) - \text{CH}_3 \) (2,3-Diethylbutane, which is wrong)
When written in expanded form:
\( \text{CH}_3 - \text{CH(CH}_3) - \text{CH(CH}_3) - \text{CH}_2 - \text{CH}_2 - \text{CH}_3 \) (3,4-Dimethylhexane, which is correct)

2. Smallest Number for Substituent: Once the principal chain is selected, it is numbered in such a way that the substituent gets the lowest number.
For example:
\( \text{CH}_3 - \text{CH}_2 - \text{CH(CH}_3) - \text{CH}_3 \) (3-Methylbutane is wrong, 2-Methylbutane is correct)
\( \text{CH}_3 - \text{CH}_2 - \text{CH} = \text{CH}_2 \) (But-3-ene is wrong, But-1-ene is correct)

Question. Explain the term – ‘Hydrocarbons’. State the two main groups of hydrocarbons with examples. Draw a chart differentiating — ‘Alkanes, Alkenes and Alkynes’ — with respect to:
1. General formula
2. Characteristic bond
3. IUPAC and the common name of the first three members and condensed/branched/electronic structural formula of each
4. Availability of electrons
5. Reactivity
6. Characteristic reaction.
Answer:
Hydrocarbons — They are aliphatic open chain organic compounds containing carbon and hydrogen only.
Molecular formula is \( \text{C}_x\text{H}_y \) where X and Y are whole numbers.
1. Saturated hydrocarbons — Homologous series of alkanes.
2. Unsaturated hydrocarbons — Series of alkynes and alkenes.

General formula :
- Alkanes — \( \text{C}_n\text{H}_{2n+2} \)
- Alkenes — \( \text{C}_n\text{H}_{2n} \)
- Alkynes — \( \text{C}_n\text{H}_{2n-2} \)

Characteristic bond :
- Alkanes → C – C single bond
- Alkenes → C = C double bond
- Alkynes → C ≡ C triple bond

IUPAC Name Condensed/branched/electronic structural formula of each:

  H     H
   \   /
    C=C
   /   \
  H     H
    

  H  H  H
  |  |  |
H-C-C=C
  |     |
  H     H
    

  H  H  H  H
  |  |  |  |
H-C-C-C=C
  |  |     |
  H  H     H
    

H-C≡C-H

  H
  |
H-C-C≡C-H
  |
  H
    

  H  H
  |  |
H-C-C-C≡C-H
  |  |
  H  H
    

Alkanes

Availability of electrons

• Alkanes — Not available
• Alkenes — Available
• Alkynes — Available

Reactivity

• Alkanes — Less reactive
• Alkenes — More reactive
• Alkynes — Most reactive

Characteristic Reaction

• Alkanes — Substitution reaction
• Alkenes — Addition reaction
• Alkynes — Addition reaction

Question. Draw the structural formula of each of the following :

ALKANE
(a) Methane
(b) Ethane
(c) Propane
(d) Butane
-Chain isomers: (i) 1-butane [n-butane], (ii) 2-methyl propane [iso-butane]
(e) Pentane
-Chain isomers: (i) 1-pentane [n-pentane], (ii) 2-methyl butane [iso-pentane], (iii) 2-2 dimethyl-propane [neo-pentane]

ALKENE
(a) No corresponding alkene
(b) Ethene
(c) Propene
(d) Butene
-Position isomers: (i) 1-butene, (ii) 2-butene
-Chain isomer: (i) 2-methyl prop-1-ene
(e) Pentene
-Position isomers: (i) 1-pentene, (ii) 2-pentene
-Chain isomer: (i) 2-methyl but-1-ene, (ii) 3-methyl but-1-ene

ALKYNE
(a) No corresponding alkyne
(b) Ethyne
(c) Propyne
(d) Butyne
-Position isomers: (i) 1-butyne, (ii) 2-butyne
(e) Pentyne
-Position isomers: (i) 1-pentyne, (ii) 2-pentyne
-Chain isomer: (i) 3-methyl but-1-yne

ALCOHOL
(a) Methanol [methyl alcohol]
(b) Ethanol [ethyl alcohol]
(c) Propanol
-Position isomers: (i) 1-propanol [n-propyl alcohol], (ii) 2-propanol [iso-propyl alcohol]
(d) Butanol
-Position isomers: (i) 1-butanol, (ii) 2-butanol
-Chain isomers: (i) 2-methyl propan-1-ol, (ii) 2-methyl propan-2-ol
(e) Pentanol
-Position isomers: (i) 1-pentanol, (ii) 2-pentanol, (iii) 3-pentanol

ALDEHYDES
(a) Methanal [formaldehyde]
(b) Ethanal [acetaldehyde]
(c) Propanal [propionaldehyde]
(d) Butanal [butyraldehyde]

CARBOXYLIC ACIDS
(a) Methanoic acid [formic acid]
(b) Ethanoic acid [acetic acid]
(c) Propanoic acid [propionic acid]
(d) Butanoic acid [butyric acid]
-Chain isomer: (i) 2-methyl propanoic acid [iso-butyric acid]

KETONES
(a) Propanone [acetone]
(b) 2-Butanone [ethyl methyl ketone]
(c) 3-Pentanone [diethyl ketone]

ETHER
(a) Methoxy methane [dimethyl ether]
(b) Methoxy ethane [ethyl methyl ether]
(c) Ethoxy ethane [diethyl ether]

ESTER
(a) Methyl methanoate [methyl formate]
(b) Methyl ethanoate [methyl acetate]
(b) Ethyl ethanoate [ethyl acetate]

ALKYL HALIDES
(a) Monochloro methane
(b) Bromoethane [ethyl bromide]
(c) Iodomethane [methyl iodide]
Answer:

ALKANE (a) Methane
Branched Structural formula:
H | H-C-H | H Condensed Structural formula: \( \text{CH}_4 \ (\text{H-CH}_3) \)

(b) Ethane
Branched Structural formula:
H H | | H-C-C-H | | H H Condensed Structural formula: \( \text{C}_2\text{H}_6 \ (\text{H}_3\text{C}-\text{CH}_3) \)

(c) Propane
Branched Structural formula:
H H H | | | H-C-C-C-H | | | H H H Condensed Structural formula: \( \text{C}_3\text{H}_8 \ (\text{H}_3\text{C}-\text{CH}_2-\text{CH}_3) \)

(d) Butane
Branched Structural formula:
H H H H | | | | H-C-C-C-C-H | | | | H H H H Condensed Structural formula: \( \text{C}_4\text{H}_{10} \ (\text{H}_3\text{C}-\text{CH}_2-\text{CH}_2-\text{CH}_3) \)

Chain isomers of Butane:
(1) 1-butane [n-butane]
Branched Structural formula:
H H H H | | | | H-C-C-C-C-H | | | | H H H H Condensed Structural formula: \( \text{CH}_3-\text{CH}_2-\text{CH}_2-\text{CH}_3 \)
(2) 2-methyl propane [iso-butane]
Branched Structural formula:
H H H | | | H-C-C-C-H | | | H | H H-C-H | H Condensed Structural formula: \( (\text{CH}_3)_3-\text{CH} \)

(e) Pentane
Branched Structural formula:
H H H H H | | | | | H-C-C-C-C-C-H | | | | | H H H H H Condensed Structural formula: \( \text{H}_3\text{C}-\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{CH}_3 \)

Chain isomers of Pentane:
(1) 1-pentane [n-pentane]
Branched Structural formula:
H H H H H | | | | | H-C-C-C-C-C-H | | | | | H H H H H Condensed Structural formula: \( \text{H}_3\text{C}-\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{CH}_3 \)
(2) 2-methyl butane [iso-pentane]
Branched Structural formula:
H H H H | | | | H-C-C-C-C-H | | | | H | H H H-C-H | H Condensed Structural formula: \( \text{H}_3\text{C}-\text{CH(CH}_3)-\text{CH}_2-\text{CH}_3 \)
(3) 2,2-dimethylpropane [neo-pentane]
Branched Structural formula:
H | H-C-H | H | H | | | H-C - C - C-H | | | H | H H-C-H | H Condensed Structural formula: \( \text{C(CH}_3)_4 \)

ALKENE (a) No corresponding alkene

(b) Ethene
Branched Structural formula:
H H \ / C=C / \ H H Condensed Structural formula: \( \text{C}_2\text{H}_4 \ (\text{H}_2\text{C}=\text{CH}_2) \)

(c) Propene
Branched Structural formula:
H H H | | / H-C - C=C | \ H H Condensed Structural formula: \( \text{C}_3\text{H}_6 \ (\text{CH}_3-\text{CH}=\text{CH}_2) \)

(d) Butene
Branched Structural formula:
H H H H | | | / H-C - C - C=C | | \ H H H Condensed Structural formula: \( \text{C}_4\text{H}_8 \ (\text{H}_3\text{C}-\text{CH}_2-\text{CH}=\text{CH}_2) \)

Position isomers of Butene:
(1) 1-Butene
Branched Structural formula:
H H H H | | | / H-C - C - C=C | | \ H H H Condensed Structural formula: \( \text{C}_4\text{H}_8 \ (\text{H}_3\text{C}-\text{CH}_2-\text{CH}=\text{CH}_2) \)
(2) 2-Butene
Branched Structural formula:
H H H H | | | | H-C - C = C - C-H | | | | H H H H Condensed Structural formula: \( \text{H}_3\text{C}-\text{CH}=\text{CH}-\text{CH}_3 \)

Chain isomers of Butene:
(3) 2-methyl prop-1-ene
Branched Structural formula:
H | H-C-H | H | | | H-C-C=C-H | | H H Condensed Structural formula: \( \text{CH}_2=\text{C(CH}_3)_2 \)

(e) Pentene
Branched Structural formula:
H H H H H | | | | | H-C = C - C - C - C-H | | | | | H H H H H Condensed Structural formula: \( \text{H}_2\text{C}=\text{CH}-\text{CH}_2-\text{CH}_2-\text{CH}_3 \)

Position isomers of Pentene:
(1) 1-pentene
Branched Structural formula:
H H H H H | | | | | H-C = C - C - C - C-H | | | | | H H H H H Condensed Structural formula: \( \text{H}_2\text{C}=\text{CH}-\text{CH}_2-\text{CH}_2-\text{CH}_3 \)
(2) 2-pentene
Branched Structural formula:
H H H H H | | | | | H-C - C = C - C - C-H | | | | | H H H H H Condensed Structural formula: \( \text{H}_3\text{C}-\text{CH}=\text{CH}-\text{CH}_2-\text{CH}_3 \)

Chain isomers of Pentene:
(1) 2-methyl but-1-ene
Branched Structural formula:
H | H-C-H | H H | | H-C - C - C = C-H | | | | H H H H Condensed Structural formula: \( \text{H}_3\text{C}-\text{CH}_2-\text{C(CH}_3)=\text{CH}_2 \)
(2) 3-methyl but-1-ene
Branched Structural formula:
H | H-C-H | H | | | H-C-C-C=C-H | | | H H H Condensed Structural formula: \( \text{H}_3\text{C}-\text{CH(CH}_3)-\text{CH}=\text{CH}_2 \)

ALKYNE (a) No corresponding alkyne

(b) Ethyne
Branched Structural formula: \( \text{H}-\text{C}\equiv\text{C}-\text{H} \)
Condensed Structural formula: \( \text{CH}\equiv\text{CH} \)

(c) Propyne
Branched Structural formula:
H | H-C-C≡C-H | H Condensed Structural formula: \( \text{H}_3\text{C}-\text{C}\equiv\text{C}-\text{H} \)

(d) Butyne
Position isomers of Butyne:
(1) 1-butyne
Branched Structural formula:
H H | | H-C - C - C≡C-H | | H H Condensed Structural formula: \( \text{H}_3\text{C}-\text{CH}_2-\text{C}\equiv\text{CH} \)
(2) 2-butyne
Branched Structural formula:
H H | | H-C - C≡C-C-H | | H H Condensed Structural formula: \( \text{H}_3\text{C}-\text{C}\equiv\text{C}-\text{CH}_3 \)

(e) Pentyne
Position isomers of Pentyne:
(1) 1-pentyne
Branched Structural formula:
H H H | | | H-C - C - C - C≡C-H | | | H H H Condensed Structural formula: \( \text{H}_3\text{C}-\text{CH}_2-\text{CH}_2-\text{C}\equiv\text{CH} \)
(2) 2-pentyne
Branched Structural formula:
H H H | | | H-C - C - C≡C-C-H | | | H H H Condensed Structural formula: \( \text{H}_3\text{C}-\text{CH}_2-\text{C}\equiv\text{C}-\text{CH}_3 \)

Chain isomers of Pentyne:
(3) 3-methyl but-1-yne
Branched Structural formula:
H | H-C-H | H | | | H-C-C-C≡C-H | | H H Condensed Structural formula: \( \text{H}_3\text{C}-\text{CH(CH}_3)-\text{C}\equiv\text{CH} \)

ALCOHOL (a) Methanol [methyl alcohol]
Branched Structural formula:
H | H-C-OH | H Condensed Structural formula: \( \text{H}_3\text{C-OH} \)

(b) Ethanol [ethyl alcohol]
Branched Structural formula:
H H | | H-C - C-OH | | H H Condensed Structural formula: \( \text{H}_3\text{C-CH}_2\text{-OH} \)

(c) Propanol
Position isomers of Propanol:
(1) 1-propanol [n-propyl alcohol]
Branched Structural formula:
H H H | | | H-C - C - C-OH | | | H H H Condensed Structural formula: \( \text{H}_3\text{C-CH}_2\text{-CH}_2\text{-OH} \)
(2) 2-propanol [iso-propyl alcohol]
Branched Structural formula:
H OH H | | | H-C - C - C-H | | | H H H Condensed Structural formula: \( \text{H}_3\text{C-CH(OH)-CH}_3 \)

(d) Butanol
Position isomers of Butanol:
(1) 1-butanol
Branched Structural formula:
H H H H | | | | H-C - C - C - C-OH | | | | H H H H Condensed Structural formula: \( \text{H}_3\text{C-CH}_2\text{-CH}_2\text{-CH}_2\text{-OH} \)
(2) 2-butanol
Branched Structural formula:
H H OH H | | | | H-C - C - C - C-H | | | | H H H H Condensed Structural formula: \( \text{H}_3\text{C-CH}_2\text{-CH(OH)-CH}_3 \)

Chain isomers of Butanol:
(i) 2-methyl propan-1-ol
Branched Structural formula:
H | H-C-H | H | H | | | H-C - C - C-OH | | | H H H Condensed Structural formula: \( \text{H}_3\text{C-CH(CH}_3\text{)-CH}_2\text{-OH} \)
(ii) 2-methyl propan-2-ol
Branched Structural formula:
H | H-C-H | H | H | | | H-C - C - C-H | | | H OH H Condensed Structural formula: \( (\text{CH}_3)_3\text{C-OH} \)

(e) Pentanol
Position isomers of Pentanol:
(i) 1-pentanol
Branched Structural formula:
H H H H H | | | | | H-C - C - C - C - C-OH | | | | | H H H H H Condensed Structural formula: \( \text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_2\text{OH} \)
(ii) 2-pentanol
Branched Structural formula:
H H H OH H | | | | | H-C - C - C - C - C-H | | | | | H H H H H Condensed Structural formula: \( \text{CH}_3\text{CH}_2\text{CH}_2\text{CH(OH)CH}_3 \)
(iii) 3-pentanol
Branched Structural formula:
H H OH H H | | | | | H-C - C - C - C - C-H | | | | | H H H H H Condensed Structural formula: \( \text{CH}_3\text{CH}_2\text{CH(OH)CH}_2\text{CH}_3 \)

ALDEHYDES (a) Methanal [formaldehyde]
Branched Structural formula:
O || H-C-H Condensed Structural formula: \( \text{H-CH=O} \) (or \( \text{HCHO} \))

(b) Ethanal [acetaldehyde]
Branched Structural formula:
H O | // H-C-C-H | H Condensed Structural formula: \( \text{H}_3\text{C-CH=O} \) (or \( \text{CH}_3\text{CHO} \))

(c) Propanal [propionaldehyde]
Branched Structural formula:
H H O | | // H-C - C-C-H | | H H Condensed Structural formula: \( \text{CH}_3\text{CH}_2\text{CHO} \)

(d) Butanal [butyraldehyde]
Branched Structural formula:
H H H O | | | // H-C - C - C-C-H | | | H H H Condensed Structural formula: \( \text{CH}_3(\text{CH}_2)_2\text{CHO} \)

CARBOXYLIC ACIDS (a) Methanoic acid [formic acid]
Branched Structural formula:
O // C-OH | H Condensed Structural formula: \( \text{HCOOH} \)

(b) Ethanoic acid [acetic acid]
Branched Structural formula:
H O | // H-C-C-OH | H Condensed Structural formula: \( \text{CH}_3\text{COOH} \)

(c) Propanoic acid [propionic acid]
Branched Structural formula:
H H O | | // H-C - C-C-OH | | H H Condensed Structural formula: \( \text{CH}_3\text{CH}_2\text{COOH} \)

(d) Butanoic acid [butyric acid]
Branched Structural formula:
H H H O | | | // H-C - C - C-C-OH | | | H H H Condensed Structural formula: \( \text{CH}_3\text{CH}_2\text{CH}_2\text{COOH} \)

Chain isomer:
(i) 2-methyl propanoic acid [iso-butyric acid]
Branched Structural formula:
H | H-C-H | H | O | | // H-C - C-C-OH | | H H Condensed Structural formula: \( (\text{CH}_3)_2\text{CHCOOH} \)

KETONES (a) Propanone [acetone]
Branched Structural formula:
H O H | // | H-C-C - C-H | | H H Condensed Structural formula: \( \text{CH}_3\text{COCH}_3 \)

(b) 2-Butanone [ethyl methyl ketone]
Branched Structural formula:
H O H H | // | | H-C-C - C - C-H | | | H H H Condensed Structural formula: \( \text{CH}_3\text{COCH}_2\text{CH}_3 \)

(c) 3-Pentanone [diethyl ketone]
Branched Structural formula:
H H O H H | | // | | H-C - C-C - C - C-H | | | | H H H H Condensed Structural formula: \( \text{CH}_3\text{CH}_2\text{COCH}_2\text{CH}_3 \)

ETHER (a) Methoxy methane [dimethyl ether]
Branched Structural formula:
H H | | H-C - O - C-H | | H H Condensed Structural formula: \( \text{CH}_3\text{-O-CH}_3 \)

(b) Methoxy ethane [ethyl methyl ether]
Branched Structural formula:
H H H | | | H-C - O - C - C-H | | | H H H Condensed Structural formula: \( \text{CH}_3\text{-O-CH}_2\text{-CH}_3 \)

(c) Ethoxy ethane [diethyl ether]
Branched Structural formula:
H H H H | | | | H-C - C - O - C - C-H | | | | H H H H Condensed Structural formula: \( \text{CH}_3\text{-CH}_2\text{-O-CH}_2\text{-CH}_3 \)

ESTER (a) Methyl methanoate [methyl formate]
Branched Structural formula:
O H // | C - O - C-H | | H H Condensed Structural formula: \( \text{HCOOCH}_3 \)

(b) Methyl ethanoate [methyl acetate]
Branched Structural formula:
H O H | // | H-C-C - O - C-H | | H H Condensed Structural formula: \( \text{CH}_3\text{COOCH}_3 \)

(b) Ethyl ethanoate [ethyl acetate]
Branched Structural formula:
H O H H | // | | H-C-C - O - C - C-H | | | H H H Condensed Structural formula: \( \text{CH}_3\text{COOCH}_2\text{CH}_3 \)

ALKYL HALIDES (a) Monochloro methane
Branched Structural formula:
H | H-C-Cl | H Condensed Structural formula: \( \text{CH}_3\text{Cl} \)

(b) Bromoethane [ethyl bromide]
Branched Structural formula:
H H | | H-C - C-Br | | H H Condensed Structural formula: \( \text{CH}_3\text{CH}_2\text{Br} \)

(c) Iodomethane [methyl iodide]
Branched Structural formula:
H | H-C-I | H Condensed Structural formula: \( \text{CH}_3\text{I} \)

KETONES

(a) Propanone

      H   O   H
      |   ||  |
  H - C - C - C - H       O
      |       |           ||
      H       H       H₃C—C—CH₃

(b) 2-Butanone

      H   O   H   H
      |   ||  |   |
  H - C - C - C - C - H   O
      |       |   |       ||
      H       H   H   H₃C—C—CH₂—CH₃

(c) 3-Pentanone

      H   H   O   H   H
      |   |   ||  |   |
  H - C - C - C - C - C - H   O
      |   |       |   |       ||
      H   H       H   H   H₃C—CH₂—C—CH₂—CH₃

ETHER

(a) Methoxy methane

      H       H
      |       |
  H - C - O - C - H       H₃C — O — CH₃
      |       |
      H       H

(b) Methoxy ethane

      H       H   H
      |       |   |
  H - C - O - C - C - H   H₃C — O — CH₂ — CH₃
      |       |   |
      H       H   H

(c) Ethoxy ethane

      H   H       H   H
      |   |       |   |
  H - C - C - O - C - C - H   H₃C — CH₂ — O — CH₂ — CH₃
      |   |       |   |
      H   H       H   H

CARBOXYLIC ACIDS

(a) Methanoic acid

  H — O — OH              H — COOH
      ||
      H

(b) Ethanoic acid

      H   O
      |   ||
  H - C - C - OH          H₃C — COOH
      |
      H

(c) Propanoic acid

      H   H   O
      |   |   ||
  H - C - C - C - OH      H₃C — CH₂ — COOH
      |   |
      H   H

(d) Butanoic acid - Chain isomers — (i) 2-methyl-propanoic acid

      H   H   H   O
      |   |   |   ||
  H - C - C - C - C - OH  H₃C — CH₂ — CH₂ — COOH
      |   |   |
      H   H   H

ALKYL HALIDES

(a) Monochloro methane

      H
      |
  H - C - Cl              CH₃ — Cl
      |
      H

(b) Bromoethane

      H   H
      |   |
  H - C - C - Br          H₃C — CH₂ — Br
      |   |
      H   H

(c) Iodomethane

      H
      |
  H - C - I               H₃C — I
      |
      H

ESTER

(a) Methyl methanoate

      O       H
      ||      |
  H - C - O - C - H       O
              |           ||
              H       H — C — O — CH₃

(b) Methyl ethanoate

      H   O       H
      |   ||      |
  H - C - C - O - C - H   O
      |           |       ||
      H           H   H₃C — C — O — CH₃

(c) Ethyl ethanoate

      H   O       H   H
      |   ||      |   |
  H - C - C - O - C - C - H   O
      |           |   |       ||
      H           H   H   H₃C — CH₂ — C — O — CH₂ — CH₃

Question. Give the IUPAC name of the compounds numbered (i) to (v).
(i)

    H  H  H  H
    |  |  |  |
H - C - C - C - C - OH
    |  |  |  |
    H CH₃ H  H

(ii)

    H  CH₃ H
    |  |  |
H - C - C - C - OH
    |  |  |
    H  CH₃ H

(iii)

    H  Br    O
    |  |     ||
H - C - C - CH - C - OH
    |  |     |
    H  H    CH₃

(iv)

    H  H  H  H
    |  |  |  |
H - C - C - C - C = O
    |  |  |
    H  CH₃ H

(v)

    H  H  O  H
    |  |  || |
H - C - C - C - C - H
    |  |     |
    H  CH₃    H

Answer:
1. Methyl butanol, 2-Methyl-1-butanol
2. 2, 2-dimethyl propanol
3. 2-Bromocyclo pentan- I -ol
4. 3-Methylbutanal
5. 3-Methyl-2-butanone

Question. Give reactions for the following:
(a) METHANE [\( \text{CH}_4 \)] from - Sodium ethanoate by - decarboxylation [sodium acetate]
(b) METHANE [\( \text{CH}_4 \)] from - Iodo methane [methyl iodide] from - an alkylhalide
(c) ETHANE [\( \text{C}_2\text{H}_6 \)] from - Sodium propanoate by - decarboxylation [sodium propionate]
(d) ETHANE [\( \text{C}_2\text{H}_6 \)] from - Bromo ethane [ethyl bromide] from - an alkylhalide
(e) ETHENE [\( \text{C}_2\text{H}_4 \)] from - Ethanol by - dehydration [ethyl alcohol]
(f) ETHENE [\( \text{C}_2\text{H}_4 \)] from - Bromoethane by - dehydrohalogenation [ethyle bromide]
(g) ETHYNE [\( \text{C}_2\text{H}_2 \)] from - Calcium carbide from - a calcium compound
(h) ETHYNE [\( \text{C}_2\text{H}_2 \)] from - 1,2, dibromoethane by - dehydrohalogenation [ethylene dibromide]
(i) ETHANOL [\( \text{C}_2\text{H}_5\text{OH} \)] from - Bromo ethane by - hydrolysis of alkylhalide [ethyl bromide]
(j) ETHANOL [\( \text{C}_2\text{H}_5\text{OH} \)] from - Ethene [ethylene] by - hydration of ethene
(k) ETHANOIC ACID [\( \text{CH}_3\text{COOH} \)] from - Ethanol [ethyl alcohol] by - oxidation of alcohol
Answer:
(a) \( \text{CH}_3\text{COONa} + \text{NaOH} \longrightarrow \text{CH}_4 + \text{Na}_2\text{CO}_3 \)
(b) \( \text{CH}_3\text{I} + 2[\text{H}] \longrightarrow \text{CH}_4 + \text{HI} \)
(c) \( \text{C}_2\text{H}_5\text{COONa} + \text{NaOH} \longrightarrow \text{C}_2\text{H}_6 + \text{Na}_2\text{CO}_3 \)
(d) \( \text{C}_2\text{H}_5\text{Br} + 2[\text{H}] \longrightarrow \text{C}_2\text{H}_6 + \text{HBr} \)

e. \( \text{C}_2\text{H}_5\text{OH} \xrightarrow[170^\circ\text{C}]{\text{conc. } \text{H}_2\text{SO}_4\text{ (excess)}} \text{CH}_2 = \text{CH}_2 + \text{H}_2\text{O} \)
    ethanol                                 ethene
    Dehydration of ethanol
    Reaction with \( \text{H}_2\text{SO}_4, 170^\circ\text{C} \)

f. \( \text{C}_2\text{H}_5\text{Br} + \text{KOH} \longrightarrow \text{CH}_2=\text{CH}_2 + \text{KBr} + \text{H}_2\text{O} \)
g. \( \text{CaC}_2 + 2\text{HOH} \longrightarrow \text{C}_2\text{H}_2 + \text{Ca(OH)}_2 \)
h. \( \text{C}_2\text{H}_4\text{Br}_2 + 2\text{KOH} \longrightarrow \text{CH} \equiv \text{CH} + 2\text{KBr} + 2\text{H}_2\text{O} \)
i. \( \text{C}_2\text{H}_5\text{Br} + \text{KOH} \longrightarrow \text{C}_2\text{H}_5\text{OH} + \text{KBr} \)
j. \( \text{C}_2\text{H}_4 + \text{H}_2\text{SO}_4\text{ (conc.)} \longrightarrow \text{C}_2\text{H}_5\text{OH} + \text{SO}_2 \)
k. \( \text{C}_2\text{H}_5\text{-OH} + \text{O} \longrightarrow \text{CH}_3\text{COOH} \)

Question. Give equations for the conversions of – Methane, Ethane, Ethene, Ethyne, Methanol, Ethanol and Ethanoic Acid.
Answer:

CONVERSION OF METHANE (\( \text{CH}_4 \)) to:

(a) Carbon tetrachloride
\( \text{CH}_4 + \text{Cl}_2 \xrightarrow{\text{diff. sunlight / uv} / \Delta} \text{CH}_3\text{Cl} + \text{HCl} \)
                                methyl chloride
\( \text{CH}_3\text{Cl} + \text{Cl}_2 \longrightarrow \text{CH}_2\text{Cl}_2 + \text{HCl} \)
    methyl chloride                 dichloromethane
\( \text{CH}_2\text{Cl}_2 + \text{Cl}_2 \longrightarrow \text{CHCl}_3 + \text{HCl} \)
                                trichloromethane
\( \text{CHCl}_3 + \text{Cl}_2 \longrightarrow \text{CCl}_4 + \text{HCl} \)
                                carbon tetrachloride
This reaction is a substitution reaction.

(b) Carbon dioxide (\( \text{CO}_2 \))
\( \text{CH}_4 + 2\text{O}_2 \longrightarrow \text{CO}_2 + 2\text{H}_2\text{O} \)
When methane is burnt in excess of air or oxygen with pale blue flame it gives carbon dioxide gas, water and heat energy. This reaction is complete oxidation reaction.

(c) Conversion of Methane to Methanol \(\rightarrow\) Methanal \(\rightarrow\) Methonic acid
\( 2\text{CH}_4 + \text{O}_2 \xrightarrow[\text{473k 120 atm.}]{\text{Cu tube}} 2\text{CH}_3\text{OH} \)
    methane                                 methanol
This reaction is carried out in a copper tube. Cu acts as a catalyst. In this reaction, methane is oxidised to methanol or methyl alcohol. In this reaction, methane is heated up to a temp, of 200°C under a pressure of 120 atm.
\( \text{CH}_4 \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7/\text{dil.H}_2\text{SO}_4]{[\text{O}]} \text{CH}_3\text{OH} \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7/\text{dil.H}_2\text{SO}_4]{[\text{O}]} \text{HCHO} \)
                                        methanol                         methanal
\( \xrightarrow[\text{K}_2\text{Cr}_2\text{O}_7/\text{dil.H}_2\text{SO}_4]{[\text{O}]} \text{HCOOH} \)
                            methanoic acid
Methane can also be converted into methanol by controlled oxidation of methane in the presence of acidified \( \text{K}_2\text{Cr}_2\text{O}_7 \).
In this reaction, methane is oxidised in a copper tube methane is heated upto a tem. of 475 k under a pressure of 120 atm. Copper tube acts as a catalyst. This is carried out as catalytic oxidation.

(d) Conversion of methane to Methanal
\( \text{CH}_4 + \text{O}_2 \xrightarrow[350-500^\circ\text{C}]{\text{MoO}} \text{HCHO} + \text{H}_2\text{O} \)
    methane                                 methanal
This reaction involves the catalytic oxidation. In this reaction, methane is heated with catalyst molybdenum oxide (MoO) at a temp. of 350 – 500°C, methanol is formed.

(e) Conversion of Methane to Ethyne (\( \text{C}_2\text{H}_2 \))
\( 2\text{CH}_4 \xrightarrow{1500^\circ\text{C}} \text{C}_2\text{H}_2 + 3\text{H}_2 \)
    methane                                 ethyne
When methane is heated to about 1500°C in an electric arc and then suddenly cooled, the product is \( \text{C}_2\text{H}_2 \) and Hydrogen.

CONVERSION OF ETHANE (\( \text{C}_2\text{H}_6 \)) to:

(a) Hexachloro ethane (\( \text{C}_2\text{Cl}_6 \))
\( \text{C}_2\text{H}_6 + \text{Cl}_2 \xrightarrow{\text{diff. sunlight / uv} / \Delta} \text{C}_2\text{H}_5\text{Cl} + \text{HCl} \)
\( \text{C}_2\text{H}_4\text{Cl}_2 + \text{Cl}_2 \longrightarrow \text{C}_2\text{H}_4\text{Cl}_2 + \text{HCl} \)
\( \text{C}_2\text{H}_4\text{Cl}_2 + \text{Cl}_2 \longrightarrow \text{C}_2\text{H}_3\text{Cl}_3 + \text{HCl} \)
\( \text{C}_2\text{H}_3\text{Cl}_3 + \text{Cl}_2 \longrightarrow \text{C}_2\text{H}_2\text{Cl}_4 + \text{HCl} \)
\( \text{C}_2\text{H}_2\text{Cl}_4 + \text{Cl}_2 \longrightarrow \text{C}_2\text{HCl}_5 + \text{HCl} \)
\( \text{C}_2\text{HCl}_5 + \text{Cl}_2 \longrightarrow \text{C}_2\text{Cl}_6 + \text{HCl} \)
This reaction is a substitution reaction.

(b) Carbon dioxide (\( \text{CO}_2 \))
\( 2\text{C}_2\text{H}_6 + 7\text{O}_2\text{ (excess)} \longrightarrow 4\text{CO}_2 + 6\text{H}_2\text{O} \)

(c) Ethanol \(\rightarrow\) Ethanal \(\rightarrow\) Ethanoic acid
\( 2\text{C}_2\text{H}_6 + \text{O}_2 \xrightarrow[200^\circ\text{C}]{\text{Cu tube}} 2\text{C}_2\text{H}_5\text{OH} \)
    ethane                                 ethanol
\( \text{C}_2\text{H}_6 + \text{O}_2 \xrightarrow[350-500^\circ\text{C}]{\text{MoO}} \text{CH}_3\text{CHO} + \text{H}_2\text{O} \)
    ethane                                 ethanal
\( \text{C}_2\text{H}_5\text{OH} + [\text{O}] \longrightarrow \text{CH}_3\text{CHO} + \text{H}_2\text{O} \)
\( \text{C}_2\text{H}_5 + 2[\text{O}] \xrightarrow{\text{K}_2\text{Cr}_2\text{O}_7/\text{dil. H}_2\text{SO}_4} \text{CH}_3\text{COOH} + \text{H}_2\text{O} \)

(d) Ethanal (\( \text{CH}_3\text{CHO} \))
\( \text{C}_2\text{H}_6 + \text{O}_2 \xrightarrow[350-500^\circ\text{C}]{\text{MoO}} \text{CH}_3\text{CHO} + \text{H}_2\text{O} \)
    ethane                                 ethanal

(e) Ethene (\( \text{C}_2\text{H}_4 \))
\( \text{C}_2\text{H}_6 \xrightarrow[\text{Al}_2\text{O}_3]{500^\circ\text{C}} \text{C}_2\text{H}_4 + \text{H}_2 \)
    ethane                                 ethene

CONVERSION OF ETHENE to:

(a) Ethane (\( \text{H}_2\text{C} - \text{CH}_2 \))
\( \text{H}_2\text{C} = \text{CH}_2 + \text{H}_2 \xrightarrow[300^\circ\text{C}]{\text{Nickel}} \text{H}_2\text{C} - \text{CH}_2 \)
    ethene (ethylene)                                         Ethane
                                                |     |                 ethane
                                                H     H

(b) 1,2, dichloroethane
\( \text{H}_2\text{C} = \text{CH}_2 + \text{Cl}_2 \xrightarrow{\text{CCl}_4} \text{H}_2\text{C} - \text{CH}_2 \)
    ethene (ethylene)                                 |     |                 1,2, dichloroethane
                                                Cl    Cl

(c) 1, 2, dibromoethane
\( \text{H}_2\text{C} = \text{CH}_2 + \text{Br}_2 \xrightarrow{\text{CCl}_4} \text{H}_2\text{C} - \text{CH}_2 \)
    ethene (ethylene)                                 |     |                 1,2, dibromoethane (colourless)
                                                Br    Br

(d) 1, 2 diiodoethane
\( \text{C}_2\text{H}_4 + \text{I}_2 \longrightarrow \text{C}_2\text{H}_4\text{I}_2 \)
                                            1, 2 diiodoethane

(e) Bromoethane
\( \text{H}_2\text{C} = \text{CH}_2 + \text{HBr} \xrightarrow{\text{room temp.}} \text{H}_2\text{C} - \text{CH}_2 \)
    ethene (ethylene)                                 |     |                 Bromoethane
                                                H    Br

\( \text{C}_2\text{H}_4 + \text{HCl} \longrightarrow \text{C}_2\text{H}_5\text{Cl} \)
                                            Chloroethane

(f) Polyethylene
\( \text{n H}_2\text{C} = \text{CH}_2 \xrightarrow[\text{high pressure catalyst}]{\text{high temp.}} (\text{H}_2\text{C} - \text{CH}_2\text{)}_n \)
                                            Polyethylene

CONVERSION OF ETHYNE to:

(a) Ethene

Chemical Reactions and Conversions

(b) 1,1,2,2-tetrachloroethane
\(\mathrm{H-C \equiv C-H + Cl_2 \xrightarrow{CCl_4} CHCl=CHCl + Cl_2 \xrightarrow{CCl_4} CH(Cl)_2-CH(Cl)_2}\) (1,1,2,2-tetrachloroethane)

(c) 1,1,2,2-tetrabromoethane
\(\mathrm{H-C \equiv C-H + Br_2 \xrightarrow{CCl_4} CHBr=CHBr + Br_2 \xrightarrow{CCl_4} CH(Br)_2-CH(Br)_2}\) (1,1,2,2-tetrabromoethane)

(d) 1,2-diiodoethane
\(\mathrm{C_2H_2 + I_2 \rightarrow C_2H_2I_2}\) (1,2-diiodoethene)

(e) 1,1-Dibromoethane
\(\mathrm{H-C \equiv C-H + HBr_2 \rightarrow H-C=C-H + HBr \rightarrow CH_3-CHBr_2}\) (1,1-Dibromoethane)

(f) Copper acetylide / Silver acetylide
\(\mathrm{HC \equiv CH + 2CuCl + 2NH_4OH \rightarrow Cu-C \equiv C-Cu \downarrow + 2NH_4Cl + 2H_2O}\) (Copper acetylide, red ppt.)
\(\mathrm{HC \equiv CH + 2AgNO_3 + 2NH_4OH \rightarrow Ag-C \equiv C-Ag \downarrow + 2NH_4NO_3 + 2H_2O}\) (Silver acetylide, white ppt.)

Conversion of Ethanol

(a) Carbon dioxide
\(\mathrm{C_2H_4 + H_2SO_4\text{ (conc.)} \xrightarrow[30\text{ atmos.}]{80^\circ\text{C}} C_2H_5-HSO_4}\) (Ethyl hydrogen sulphate)
\(\mathrm{C_2H_5-HSO_4 \xrightarrow{80^\circ\text{C}} H_2O \rightarrow C_2H_5OH + H_2SO_4}\) (Ethanol)
\(\mathrm{C_2H_5OH + 3O_2 \rightarrow 2CO_2 + 3H_2O}\) (Combustion of ethanol)

(b) Ethanal to Ethanoic acid
\(\mathrm{C_2H_5OH \xrightarrow[K_2Cr_2O_7 / \text{dil. } H_2SO_4]{[O]} CH_3-CHO \xrightarrow[K_2Cr_2O_7 / \text{dil. } H_2SO_4]{[O]} CH_3-COOH}\) (Oxidation of ethanol)

(c) Sodium ethoxide
\(\mathrm{2C_2H_5OH + 2Na \rightarrow 2C_2H_5ONa + H_2}\) (Reaction with sodium)

(d) Ethyl ethanoate
\(\mathrm{C_2H_5OH + CH_3COOH \xrightarrow{\text{conc. } H_2SO_4\text{ or dry } HCl\text{ gas}} CH_3-COO-C_2H_5 + H_2O}\) (Reaction with acetic acid)

(e) Ethene
\(\mathrm{C_2H_5OH \xrightarrow[170^\circ\text{C}]{\text{conc. } H_2SO_4\text{ (excess)}} CH_2=CH_2 + H_2O}\) (Dehydration of ethanol)

Conversion of Ethanoic Acid (Acetic Acid)

(a) Sodium acetate (\(\mathrm{CH_3COONa}\))
\(\mathrm{CH_3COOH + NaOH \rightarrow CH_3COONa + H_2O}\) (Reaction with NaOH)

(b) Calcium acetate
\(\mathrm{2CH_3COOH + Ca(OH)_2 \rightarrow Ca(C_2H_3O_2)_2 + 2H_2O}\)

(c) Ammonium acetate
\(\mathrm{CH_3COOH + NH_4OH \rightarrow C_2H_3O_2NH_4 + H_2O}\)

(d) Ethyl ethanoate
\(\mathrm{CH_3COOH + C_2H_5OH \xrightarrow{\text{conc. } H_2SO_4\text{ or dry } HCl\text{ gas}} CH_3COOC_2H_5 + H_2O}\)

Question. Give reasons for:
1. alkanes are said to be saturated organic compounds
2. alkenes are known as olefins
3. alkenes are more reactive than alkanes
4. ethanoic acid is known as an aliphatic monocarboxylic acid.
Answer:
1. Alkanes do not undergo addition reactions and that is why they are called saturated hydrocarbons or saturated organic compounds. In alkanes, all the four valencies of carbon atoms are fully satisfied by forming single covalent bonds.
2. Alkenes are called olefins because alkenes on treatment with halogens form oily products (Latin: oleum = oil, ficare = to make).
3. Due to the presence of \(\mathrm{C=C}\) (carbon-carbon double bond), alkenes are more reactive than alkanes.
4. Ethanoic acid (\(\mathrm{CH_3-COOH}\)) contains only one \(\mathrm{-COOH}\) group (carboxylic acid group); that is why it is called a monocarboxylic acid. As ethanoic acid does not contain a benzene ring, it is an aliphatic monocarboxylic acid.

Question. Explain the terms:
1. Denatured alcohol
2. Glacial acetic acid
3. Esterification
Answer:
1. Denatured alcohol - Ethyl alcohol containing pyridine or copper sulphate is termed denatured alcohol. It is used for industrial applications only and hence made undrinkable.
2. Glacial acetic acid - Anhydrous acetic acid on cooling below \(16.5^\circ\text{C}\) crystallizes out in the pure form, forming a crystalline mass resembling ice. Hence, pure acetic acid is called glacial acetic acid.
3. Esterification - It is known as the condensation of an alcohol with an acid. Acetic acid on heating with an alcohol and a dehydrating agent [conc. \(\mathrm{H_2SO_4}\)] gives an ester - ethyl acetate.

Question. Give a chemical test to distinguish between:
1. Ethane, ethene and ethyne
2. Ethanol and ethanoic acid.
Answer:
1. Tests to distinguish between ethane, ethene and ethyne:

• Bromine water test: Pass the gas through \(\mathrm{Br_2}\) water.
  Ethane: Brown colour of \(\mathrm{Br_2}\) water is not discharged.
  Ethene: Brown colour of \(\mathrm{Br_2}\) water is discharged.
  Ethyne: Brown colour of \(\mathrm{Br_2}\) water is discharged.
• Baeyer's reagent test: Pass the gas through Baeyer's reagent (alkaline solution of \(\mathrm{KMnO_4}\)).
  Ethane: Purple colour of Baeyer's reagent is not discharged.
  Ethene: Purple colour of Baeyer's reagent is discharged.
  Ethyne: Purple colour of Baeyer's reagent is discharged.
• Ammoniacal cuprous chloride test: Pass the gas through ammoniacal cuprous chloride solution.
  Ethane: No ppt.
  Ethene: No ppt.
  Ethyne: Red ppt. of copper acetylide is formed.
• Ammoniacal silver nitrate test: Pass the gas through ammoniacal silver nitrate solution.
  Ethane: No ppt.
  Ethene: No ppt.
  Ethyne: White ppt. of silver acetylide is formed.

2. Tests to distinguish between ethanol and ethanoic acid:

• Litmus test: Add a few drops of blue litmus solution to the given liquid.
  Ethanol: No change in colour.
  Ethanoic acid: Blue litmus turns red.
• Sodium carbonate test: Add a pinch of sodium carbonate to the given liquid.
  Ethanol: No action.
  Ethanoic acid: Brisk effervescence with the evolution of \(\mathrm{CO_2}\).

Question. Give the main uses of:
1. Methane
2. Ethane
3. Ethene
4. Ethyne
5. Ethanol
6. Ethanoic acid.
Answer:
(1) Methane and (2) Ethane:
(a) Illuminant and domestic fuel: In the form of natural gas or gobar gas. Hydrocarbons have high calorific value, are easily combustible, and the reaction is exothermic, releasing heat energy. Hence they are excellent fuels.
(b) In manufacture of chemicals used as:
1. Chloroform: Solvent for rubber, waxes. Used as an anesthetic.
2. Carbon black: A black pigment in shoe polishes, printers' ink, etc.
3. Formaldehyde: An antiseptic, preservative for biological specimens.
4. Methanol: Solvent for varnishes, anti-freeze for automobiles.
5. Ethanol: Solvent for resins, a low-freezing liquid in thermometers.

(3) Ethene:
(a) Production of oxy-ethylene torch: For welding purposes and cutting metals.
(b) Ripening of green fruits: Artificial ripening and preservation of fruits.
(c) Catalytic hydrogenation: Used in hardening of oils.
(d) Manufacturing of:
1. Synthetic chemicals: Ethylene glycol [anti-freeze], diethyl ether [solvent], ethylene oxide [fumigant], mustard gas [chemical warfare].
2. Polymers: Polyethylene, polyvinyl chloride [P.V.C.] - used in packaging, insulators, containers, raincoats, etc.

(4) Ethyne:
(a) It is used for producing oxy-acetylene flame for welding and cutting purposes as it produces temperatures as high as \(3500^\circ\text{C}\).
(b) It is used as an illuminant in oxyacetylene lamps.
(c) It is used in the manufacture of solvents like westron (\(\mathrm{C_2H_2Cl_4}\)) and westrosol (\(\mathrm{CHCl=CCl_2}\)).

(5) Ethanol:
(a) As a solvent: For gums and resins.
(b) In thermometers and spirit levels: Low freezing mobile liquid, [freezing point \(-114.1^\circ\text{C}\)].
(c) In manufacture of chemicals: Acetaldehyde [dyes], acetic acid [manufacture of vinegar], chloroform [antiseptic], diethyl ether [anesthetic].

(6) Ethanoic acid:
(a) It is used as a solvent for many organic reactions.
(b) It is used as vinegar for preparing pickles, etc.
(c) It is used for preparing various organic compounds like acetone, acetic anhydride, esters, etc.
(d) It is used as a coagulating agent in rubber industries.
(e) It is used for making perfumes and medicines.

UNIT TEST PAPER 8 — ORGANIC CHEMISTRY

Question. Draw the branched structural formula of the following organic compounds whose IUPAC names are given below:
1. Pent-1-ene
2. But-2-yne
3. 3-methyl pentane
4. 2-methyl-prop-1-ene
5. Pentane-3-ol
6. 1,1,2,2 tetrabromoethane
7. 2-methyl butan-2-ol
8. 2,2 dimethylpropan-1-ol
9. 2,2 dimethyl propane
10. 2-bromo-4-chloro pentane
Answer:
1. \(\mathrm{H_3C-CH_2-CH_2-CH=CH_2}\)
2. \(\mathrm{H_3C-C \equiv C-CH_3}\)
3. \(\mathrm{H_3C-CH_2-CH(CH_3)-CH_2-CH_3}\)
4. \(\mathrm{H_2C=C(CH_3)_2}\)
5. \(\mathrm{H_3C-CH_2-CH(OH)-CH_2-CH_3}\)
6. \(\mathrm{CH(Br)_2-CH(Br)_2}\)
7. \(\mathrm{H_3C-CH_2-C(OH)(CH_3)-CH_3}\)
8. \(\mathrm{(H_3C)_3C-CH_2-OH}\)
9. \(\mathrm{(H_3C)_4C}\)
10. \(\mathrm{H_3C-CH(Br)-CH_2-CH(Cl)-CH_3}\)

Question. Select the correct answer from the choice in brackets: The vapour density of the fifth member of the homologous series of alkanes.
(a) 22
(b) 36
(c) 29
Answer: (b) 36

Question. Select the correct answer from the choice in brackets: The isomer of pentane which has '1' C atom attached to '4' other C atoms.
(a) n-pentane
(b) iso-pentane
(c) neo-pentane
Answer: (c) neo-pentane

Question. Select the correct answer from the choice in brackets: The IUPAC name of the product of reaction of ethylene with hydrogen bromide.
(a) ethyl bromide
(b) bromoethane
(c) dibromoethane
Answer: (b) bromoethane

Question. Select the correct answer from the choice in brackets: The IUPAC name of methyl acetylene.
(a) 1-butyne
(b) propyne
(c) ethyne
Answer: (b) propyne

Question. Select the correct answer from the choice in brackets: The functional group in ethanoic acid.
(a) aldehydic
(b) carboxyl
(c) hydroxyl
Answer: (b) carboxyl

Question. Give balanced equations for the following conversions:
1. \(\text{1,2, dibromoethane} \xrightarrow{A} \text{Acetylene} \xrightarrow{B} \text{Silver acetylide}\)
2. \(\text{Ethanol} \xrightarrow{C} \text{Ethene} \xleftarrow{D} \text{Ethyl iodide}\)
3. \(\text{Bromoethane} \xrightarrow{E} \text{Ethane} \xleftarrow{F} \text{Sodium propanoate}\)
4. \(\text{Sodium ethanoate} \xrightarrow{G} \text{Mars gas} \xrightarrow{G_1} \text{Methanol} \xrightarrow{G_2} \text{Methanal} \xrightarrow{G_3} \text{Methanoic acid}\)
5. \(\text{Sodium acetate} + \text{H}_2 \xrightarrow{H} \text{Acetic acid} \xrightarrow{H_1} \text{Ethyl ethanoate}\)
Answer:
1. \(\mathrm{CH_2Br-CH_2Br + 2KOH \rightarrow CH \equiv CH + 2KBr + 2H_2O}\)
\(\mathrm{H-C \equiv C-H + 2AgNO_3 + 2NH_4OH \xrightarrow{(B)} Ag-C \equiv C-Ag + 2NH_4NO_3 + 2H_2O}\)
2. \(\mathrm{CH_3CH_2OH \xrightarrow[170^\circ\text{C}]{\text{conc. } H_2SO_4} H-C \equiv C-H + H_2O}\) (Wait, ethene is formed: \(\mathrm{H_2C=CH_2 + H_2O}\))
\(\mathrm{CH_3-CH_2-I + NaOH\text{ (alc.)} \rightarrow CH_2=CH_2 + NaI + H_2O}\)
3. \(\mathrm{C_2H_5Br + 2[H] \xrightarrow{\text{ether}} C_2H_6 + HBr}\)
\(\mathrm{CH_3-CH_2-COONa + NaOH\text{(s)} \xrightarrow[\text{(F)}]{\text{CaO}/\Delta} Na_2CO_3 + CH_3-CH_3 \uparrow}\)
4. \(\mathrm{CH_3COONa + NaOH \xrightarrow{\text{CaO}} CH_4 + Na_2CO_3}\)
\(\mathrm{CH_4 + [O] \xrightarrow[\text{Oxidation }(G_1)]{K_2Cr_2O_7 / \text{H}^+} CH_3OH}\)
\(\mathrm{CH_3OH + [O] \xrightarrow[\text{Oxidation }(G_2)]{K_2Cr_2O_7 / \text{H}^+} HCHO + 2H_2O}\)
\(\mathrm{HCHO + [O] \xrightarrow[\text{Oxidation }(G_3)]{K_2Cr_2O_7 / \text{H}^+} HCOOH}\)
5. \(\mathrm{CH_3COOH + NaOH \rightarrow CH_3COONa + H_2O}\)
\(\mathrm{CH_3COOH + C_2H_5OH \xrightarrow[\text{Warm }(H_1)]{\text{conc. } H_2SO_4} CH_3COOC_2H_5 + H_2O}\)

Question. Select from the letters A to I the correct answer corresponding to the statement: The organic compound which forms carbon tetrachloride on reaction with chlorine.
A : Ammoniacal CuCl₂
B : Trichloromethane
C : Trichloroethane
D : Bromine soln.
E : Aqueous KOH
F : Ethene
G : Sodalime
H : Ethanol
I : Ethyne
Answer: B : Trichloromethane
Explanation: \(\mathrm{CHCl_3 + Cl_2 \xrightarrow{Sunlight} CCl_4 + HCl}\)

Question. Select from the letters A to I the correct answer corresponding to the statement: The reagent which can distinguish between ethene and ethyne.
A : Ammoniacal CuCl₂
B : Trichloromethane
C : Trichloroethane
D : Bromine soln.
E : Aqueous KOH
F : Ethene
G : Sodalime
H : Ethanol
I : Ethyne
Answer: A : Ammoniacal CuCl₂
Explanation: Only ethyne gives red ppt. of dicopper acetylide with ammoniacal \(\mathrm{Cu_2Cl_2}\) or \(\mathrm{CuCl}\).

Question. Select from the letters A to I the correct answer corresponding to the statement: The substance which reacts with bromoethane to give ethanol.
A : Ammoniacal CuCl₂
B : Trichloromethane
C : Trichloroethane
D : Bromine soln.
E : Aqueous KOH
F : Ethene
G : Sodalime
H : Ethanol
I : Ethyne
Answer: E : Aqueous KOH
Explanation: \(\mathrm{CH_3CH_2Br + KOH(aq.) \rightarrow CH_3CH_2OH + KBr + H_2O}\)

Question. Select from the letters A to I the correct answer corresponding to the statement: The substance which gives bromoethane on reaction with hydrogen bromide.
A : Ammoniacal CuCl₂
B : Trichloromethane
C : Trichloroethane
D : Bromine soln.
E : Aqueous KOH
F : Ethene
G : Sodalime
H : Ethanol
I : Ethyne
Answer: F : Ethene
Explanation: \(\mathrm{H_2C=CH_2 + HBr \rightarrow H_3C-CH_2Br}\)

Question. Select from the letters A to I the correct answer corresponding to the statement: The substance which reacts with acetic acid to give \(\mathrm{CH_3COOC_2H_5}\).
A : Ammoniacal CuCl₂
B : Trichloromethane
C : Trichloroethane
D : Bromine soln.
E : Aqueous KOH
F : Ethene
G : Sodalime
H : Ethanol
I : Ethyne
Answer: H : Ethanol
Explanation: \(\mathrm{CH_3COOH + C_2H_5OH \xrightarrow{\text{conc. } H_2SO_4} CH_3COOC_2H_5 + H_2O}\)

Question. Give balanced equations for the following conversions:
1. An alkyne to an alkene.
2. An alkene to an alkane.
3. An alkane to an alcohol.
4. An alcohol to an alkene.
5. A carboxylic acid to an ammonium salt.
Answer:
1. \(\mathrm{H-C \equiv C-H + H_2 \xrightarrow[300^\circ\text{C}]{\text{Ni}} H_2C=CH_2}\)
2. \(\mathrm{H_2C=CH_2 + H_2 \xrightarrow[300^\circ\text{C}]{\text{Ni}} H_3C-CH_3}\)
3. \(\mathrm{2CH_4 + O_2 \xrightarrow[200^\circ\text{C}]{\text{Cutube}} 2CH_3OH}\)
4. \(\mathrm{CH_3CH_2OH \xrightarrow[170^\circ\text{C}]{\text{conc. } H_2SO_4} CH_2=CH_2 + H_2O}\)
5. \(\mathrm{CH_3COOH + NH_4OH \rightarrow CH_3COONH_4 + H_2O}\)

Question. Give reasons for the following: Concentrated sulphuric acid may be added during esterification of acetic acid.
Answer: Conc. \(\mathrm{H_2SO_4}\), a strong dehydrating agent, helps in the removal of water, thus shifting the equilibrium in the forward direction, resulting in the formation of more of ethyl acetate (ester).

Question. Give reasons for the following: Isomers belonging to the same homologous series may differ in physical properties but not in chemical properties.
Answer: Isomers of the same homologous series have the same functional group (if any) and as such have similar chemical properties. As isomers are different compounds, they differ in one or more of their physical properties.

Question. Give reasons for the following: A given organic compound can be assigned only one name on the basis of the IUPAC system.
Answer: This statement is not correct. Correct statement is: An organic compound may have more than one IUPAC name (out of all these, one is a preferred IUPAC name) but two compounds cannot have the same IUPAC name because this may lead to confusion.

Question. Give reasons for the following: Substitution reactions are characteristic reactions of saturated organic compounds only.
Answer: Addition reactions are not possible in case of saturated organic compounds. Saturated organic compounds can only undergo substitution reactions.

Question. Give reasons for the following: Acetic acid is considered an aliphatic monocarboxylic acid.
Answer: Acetic acid or ethanoic acid, \(\mathrm{CH_3COOH}\) has one carboxylic acid group (\(\mathrm{-COOH}\)). Hence it is a monocarboxylic acid. As it has no benzene ring in it, it is not aromatic and hence it is an aliphatic monocarboxylic acid.