CH:9 Carbon Compounds Class 10th Solutions | Carbon Compounds SSC Class 10 Questions And Answers
Match the pairs.
| Group 'A' | Group 'B' |
|---|---|
| C₂H₆ | 3. Saturated hydrocarbon |
| C₂H₂ | 4. Triple bond |
| CH₄O | 2. Molecular formula of an alcohol |
| C₃H₆ | 1. Unsaturated hydrocarbon |
Explanation:
Solution 1: Scientific and Exam-Oriented Answer
C₂H₆ (Ethane) is a saturated hydrocarbon as it contains only single bonds.
C₂H₂ (Ethyne) is an alkyne with a triple bond between carbon atoms.
CH₄O (Methanol) is an alcohol as it contains the hydroxyl (-OH) functional group.
C₃H₆ (Propene) is an unsaturated hydrocarbon with a double bond between carbon atoms.
Solution 2: Simple and Understandable Answer
C₂H₆ (Ethane): It belongs to the alkane family, meaning it has only single bonds.
C₂H₂ (Ethyne): This is an alkyne, which means it has a triple bond.
CH₄O (Methanol): It is an alcohol because it has the -OH group.
C₃H₆ (Propene): This is an alkene, meaning it has a double bond.
Draw an electron dot structure of the following molecule (Without showing the circle): Methane (CH₄)
Solution 1: Scientific and Exam-Oriented Answer
The electron dot structure of Methane (CH₄) represents how the valence electrons are shared between the carbon and hydrogen atoms.
Electron dot structure of CH₄:
H
|
H — C — H
|
H
- Carbon (C) has 4 valence electrons and forms 4 covalent bonds with Hydrogen (H) atoms.
- Each hydrogen atom shares 1 electron with carbon, forming a stable octet.
Representation using electron dots:
H
.
H : C : H
.
H
Solution 2: Simple and Understandable Answer
- Methane (CH₄) consists of one carbon (C) atom bonded to four hydrogen (H) atoms.
- Carbon shares its four valence electrons with hydrogen, making four single bonds.
- This forms a stable molecule where all atoms follow the octet rule.
Simple diagram:
H
|
H — C — H
|
H
Each hydrogen shares one electron with carbon, ensuring stability.
Draw an electron dot structure of the following molecule (Without showing the circle): Ethene (C₂H₄)
Solution 1: Scientific and Exam-Oriented Answer
Ethene (C₂H₄) is an unsaturated hydrocarbon belonging to the alkene family. It contains a double bond between two carbon atoms.
Electron dot structure of C₂H₄:
H H
\ /
C = C
/ \
H H
- Each carbon (C) atom has four valence electrons.
- The two carbon atoms share two pairs of electrons, forming a double bond (C=C).
- Each hydrogen (H) atom forms a single covalent bond with carbon, completing the valence shell.
Representation using electron dots:
H H
: :
H : C :: C : H
: :
H H
Solution 2: Simple and Understandable Answer
- Ethene (C₂H₄) consists of two carbon atoms and four hydrogen atoms.
- The carbon atoms form a double bond (C=C) to satisfy the octet rule.
- Each hydrogen atom shares one electron with carbon, forming single bonds.
Simple diagram:
H H
| |
C = C
| |
H H
Since ethene has a double bond, it is classified as an unsaturated hydrocarbon (alkene).
Draw an electron dot structure of the following molecule (Without showing the circle): Methanol (CH₃OH)
Solution 1: Scientific and Exam-Oriented Answer
Methanol (CH₃OH) is a simple alcohol consisting of one carbon (C) atom, four hydrogen (H) atoms, and one hydroxyl (OH) group.
Electron dot structure of CH₃OH:
- The carbon (C) atom forms four single covalent bonds (three with hydrogen and one with oxygen).
- The oxygen (O) atom has two lone pairs of electrons.
- The hydroxyl (-OH) group makes methanol an alcohol.
Representation using electron dots:
H
| ..
H : C : O : H
| ..
H
Solution 2: Simple and Understandable Answer
- Methanol (CH₃OH) consists of one carbon (C) atom, three hydrogen (H) atoms, and one hydroxyl (OH) group.
- Carbon forms single bonds with three hydrogen atoms and one single bond with oxygen.
- Oxygen has two lone pairs of electrons, which makes it slightly negative.
Simple diagram:
H
|
H - C - O - H
|
H
Since methanol has an -OH group, it is classified as an alcohol.
Draw an electron dot structure of the following molecule (Without showing the circle): Water (H₂O)
Solution 1: Scientific and Written Exam Answer
Water (H₂O) is a covalent molecule consisting of two hydrogen (H) atoms and one oxygen (O) atom. Oxygen has six valence electrons, and hydrogen has one valence electron each. The oxygen atom forms two single covalent bonds with two hydrogen atoms.
Electron dot structure of H₂O:
..
H : O : H
..
- The oxygen (O) atom has two lone pairs of electrons.
- The molecule has a bent or V-shape due to lone pair repulsion, making water a polar molecule.
- Water exhibits strong hydrogen bonding due to its dipole nature.
Solution 2: Simple and Understandable Answer
- Water (H₂O) consists of one oxygen atom and two hydrogen atoms.
- Oxygen forms single bonds with hydrogen atoms to complete their octet.
- Oxygen also has two extra pairs of electrons, which make the molecule slightly bent in shape.
Simple diagram:
..
H : O : H
..
This structure explains why water is a liquid at room temperature and has strong intermolecular forces.
Draw all possible structural formulae of the compound from the given molecular formula: C₃H₈
Solution 1: Scientific and Written Exam Answer
The molecular formula C₃H₈ represents propane, which is a member of the alkane family. The general formula for alkanes is:
$$ C_nH_{2n+2} $$
For n = 3:
$$ C_3H_8 $$
Alkanes are saturated hydrocarbons, meaning they contain only single bonds between carbon atoms.
Possible structural formulae of propane (C₃H₈):
1. Straight-chain structure (n-Propane):
H H H
| | |
H - C - C - C - H
| | |
H H H
- This is the only possible structure for propane, as it contains three carbon atoms arranged in a straight chain with single bonds.
- Since all carbon atoms follow the valency rule (four bonds per carbon), there is no possibility of an isomer for propane.
Solution 2: Simple and Understandable Answer
- The molecular formula C₃H₈ belongs to the alkane family.
- In propane, three carbon atoms are connected in a single chain, and each carbon forms four single bonds.
- There is only one possible structural formula for propane.
Simple representation:
H H H
| | |
H - C - C - C - H
| | |
H H H
Since propane has only one way to arrange its atoms, there are no structural isomers.
Draw all possible structural formulae of the compound from the given molecular formula: C₄H₁₀
Solution 1: Scientific and Written Exam Answer
The molecular formula C₄H₁₀ corresponds to butane, which is a member of the alkane family. The general formula for alkanes is:
$$ C_nH_{2n+2} $$
For n = 4:
$$ C_4H_{(2×4)+2} = C_4H_{10} $$
Butane (C₄H₁₀) is a saturated hydrocarbon, meaning it contains only single bonds. It has two possible structural isomers:
1. Straight-chain butane (n-Butane):
H H H H
| | | |
H - C - C - C - C - H
| | | |
H H H H
- This structure consists of four carbon atoms in a continuous chain.
2. Branched-chain butane (Iso-Butane or 2-Methylpropane):
H H H
| | |
H - C - C - C - H
| |
H C - H
|
H
- In this form, three carbon atoms form a straight chain, and the fourth carbon is attached as a branch (methyl group) to the second carbon.
Key Points:
- Both n-butane and iso-butane are structural isomers because they have the same molecular formula (C₄H₁₀) but different structures.
- These isomers exhibit different physical properties, such as boiling points and melting points.
Solution 2: Simple and Understandable Answer
- The molecular formula C₄H₁₀ represents butane, which belongs to the alkane family.
- Butane has two possible structures:
1. Normal butane (n-Butane):
H - C - C - C - C - H
| | | |
H H H H
- This is a straight-chain structure.
2. Iso-Butane (2-Methylpropane):
H H H
| | |
H - C - C - C - H
| |
H C - H
|
H
- This is a branched structure.
- The difference in structure affects the properties of each form.
Butane and iso-butane are isomers, meaning they have the same chemical formula but different arrangements of atoms.
Draw all possible structural formulae of the compound from the given molecular formula: C₃H₄
Solution 1: Scientific and Written Exam Answer
The molecular formula C₃H₄ represents hydrocarbons with either triple bonds (alkynes) or multiple double bonds (alkadienes). The possible structures for C₃H₄ are:
1. Propyne (Methylacetylene) - An Alkyne
H - C ≡ C - CH₃
- This is a linear alkyne structure where a triple bond exists between two carbon atoms.
2. Propadiene (Allene) - A Diene
H₂C = C = CH₂
- This structure contains two double bonds between carbon atoms (a cumulene).
Key Points:
- Both structures follow the valency rule of carbon (each carbon forms four bonds).
- Propyne belongs to the alkyne family, while propadiene belongs to the diene family.
- Both compounds exhibit different physical and chemical properties.
Solution 2: Simple and Understandable Answer
- The molecular formula C₃H₄ represents hydrocarbons with triple or double bonds.
- There are two possible structures:
1. Propyne (Methylacetylene):
H - C ≡ C - CH₃
- It has a triple bond between two carbon atoms.
2. Propadiene (Allene):
H₂C = C = CH₂
- It has two double bonds between carbon atoms.
These are isomers because they have the same formula (C₃H₄) but different structures and properties.
Explain the term Structural Isomerism with an example.
Solution 1: Scientific and Written Exam Answer
Structural Isomerism is a phenomenon in which compounds have the same molecular formula but different structural arrangements of atoms. These differences arise due to variations in the connectivity of atoms, leading to different physical and chemical properties.
Types of Structural Isomerism:
- Chain Isomerism: Different carbon chain arrangements.
- Position Isomerism: Functional group positioned differently.
- Functional Isomerism: Different functional groups.
- Metamerism: Unequal distribution of alkyl groups in ethers or amines.
- Tautomerism: Rapid interconversion between two structures.
Example:
Butane (C₄H₁₀) has two structural isomers:
1. n-Butane (Straight-chain)
H H H H
| | | |
H - C - C - C - C - H
| | | |
H H H H
2. Iso-butane (Branched-chain)
H H
| |
H - C - C - H
| |
H - C - H
|
H
Both have the same molecular formula (C₄H₁₀) but differ in structure.
Solution 2: Simple and Understandable Answer
Structural Isomerism means that two or more compounds have the same number of atoms (same molecular formula) but different arrangements of atoms. This changes their physical and chemical properties.
Example: Butane (C₄H₁₀) has two structures:
1. n-Butane: A straight-chain form.
H H H H
| | | |
H - C - C - C - C - H
| | | |
H H H H
2. Iso-butane: A branched-chain form.
H H
| |
H - C - C - H
| |
H - C - H
|
H
Both have the same number of carbon and hydrogen atoms but different shapes, leading to different properties.
Structural isomers have unique boiling points, melting points, and reactivity.
Explain the following term with an example: Covalent Bond
Solution 1: Scientific and Written Exam Answer
A Covalent Bond is a type of chemical bond that involves the sharing of electrons between atoms to achieve stability. This occurs between non-metal atoms that have similar electronegativities.
Types of Covalent Bonds:
- Single Covalent Bond: One pair of electrons is shared (e.g., H₂, Cl₂).
- Double Covalent Bond: Two pairs of electrons are shared (e.g., O₂, CO₂).
- Triple Covalent Bond: Three pairs of electrons are shared (e.g., N₂, C₂H₂).
Example: Water (H₂O)
In water, each hydrogen (H) shares one electron with oxygen (O), forming a single covalent bond.
H : O : H
Oxygen shares electrons with two hydrogen atoms, creating a stable molecule.
Solution 2: Simple and Understandable Answer
A Covalent Bond is a type of bond where two atoms share electrons to become stable.
Example: Water (H₂O)
Oxygen (O) needs 2 more electrons to become stable, and hydrogen (H) needs 1 more electron. So, each hydrogen shares 1 electron with oxygen.
H - O - H
Because of this sharing, all atoms become stable.
Other Examples: Oxygen gas (O₂), Carbon dioxide (CO₂), and Methane (CH₄).
Explain the following term with an example: Hetero Atom in a Carbon Compound
Solution 1: Scientific and Written Exam Answer
A hetero atom in a carbon compound is any atom other than carbon (C) and hydrogen (H) that is present in the molecular structure. These hetero atoms replace one or more carbon or hydrogen atoms in the organic compound and usually belong to elements like oxygen (O), nitrogen (N), sulfur (S), phosphorus (P), or halogens (F, Cl, Br, I).
Example: Ethanol (C₂H₅OH)
H H
| |
H - C - C - O - H
| |
H H
In ethanol, the oxygen (O) atom is a hetero atom as it is different from carbon and hydrogen.
Solution 2: Simple and Understandable Answer
A hetero atom is any atom in an organic compound that is not carbon (C) or hydrogen (H). These atoms give special properties to the compound.
Example: Ethanol (C₂H₅OH) has an oxygen (O) atom, which makes it an alcohol.
H H
| |
H - C - C - O - H
| |
H H
Since oxygen is different from carbon and hydrogen, it is called a hetero atom.
Other Examples:
- Ammonia (NH₃): Contains nitrogen as a hetero atom.
- Methanol (CH₃OH): Contains oxygen as a hetero atom.
- Chloroethane (C₂H₅Cl): Contains chlorine as a hetero atom.
Explain the following term with an example: Functional Group
Solution 1: Scientific and Written Exam Answer
A functional group is an atom or a group of atoms within an organic molecule that determines its chemical properties and reactions. It is the reactive part of the molecule and remains unchanged during chemical reactions.
Examples of Common Functional Groups:
| Functional Group | Formula | Class of Compound | Example |
|---|---|---|---|
| Hydroxyl | -OH | Alcohol | Ethanol (C₂H₅OH) |
| Carboxyl | -COOH | Carboxylic Acid | Acetic Acid (CH₃COOH) |
| Aldehyde | -CHO | Aldehyde | Formaldehyde (HCHO) |
| Ketone | -CO- | Ketone | Acetone (CH₃COCH₃) |
| Amine | -NH₂ | Amine | Methylamine (CH₃NH₂) |
Example: Ethanol (C₂H₅OH) contains the hydroxyl (-OH) functional group, which makes it an alcohol.
H H
| |
H - C - C - O - H
| |
H H
Solution 2: Simple and Understandable Answer
A functional group is a specific part of a molecule that determines how it behaves in chemical reactions.
Example: Alcohols have a hydroxyl (-OH) functional group. One example is ethanol (C₂H₅OH), which is present in alcoholic beverages.
H H
| |
H - C - C - O - H
| |
H H
Some common functional groups are:
- -OH (Hydroxyl): Found in alcohols (e.g., Ethanol - C₂H₅OH)
- -COOH (Carboxyl): Found in acids (e.g., Acetic Acid - CH₃COOH)
- -CHO (Aldehyde): Found in aldehydes (e.g., Formaldehyde - HCHO)
Explain the following term with an example: Alkane
Solution 1: Scientific and Written Exam Answer
Alkanes are saturated hydrocarbons composed of carbon (C) and hydrogen (H) atoms, connected by single covalent bonds. They follow the general formula:
General Formula: $$ C_nH_{2n+2} $$
Since alkanes contain only single bonds, they are chemically stable and primarily undergo combustion and substitution reactions.
Examples of Alkanes:
| Name | Molecular Formula | Structural Formula | Common Use |
|---|---|---|---|
| Methane | CH₄ |
H
|
H - C - H
|
H
|
Natural gas, fuel |
| Ethane | C₂H₆ |
H H
| |
H - C - C - H
| |
H H
|
LPG gas, refrigerant |
| Propane | C₃H₈ |
H H H
| | |
H - C - C - C - H
| | |
H H H
|
Cooking fuel, heating |
| Butane | C₄H₁₀ |
H H H H
| | | |
H - C - C - C - C - H
| | | |
H H H H
|
Lighter gas, LPG |
| Pentane | C₅H₁₂ |
H H H H H
| | | | |
H - C - C - C - C - C - H
| | | | |
H H H H H
|
Solvent, gasoline |
| Hexane | C₆H₁₄ |
H H H H H H
| | | | | |
H - C - C - C - C - C - C - H
| | | | | |
H H H H H H
|
Industrial solvent |
| Heptane | C₇H₁₆ |
H H H H H H H
| | | | | | |
H - C - C - C - C - C - C - C - H
| | | | | | |
H H H H H H H
|
Used in petrol |
| Octane | C₈H₁₈ |
H H H H H H H H
| | | | | | | |
H - C - C - C - C - C - C - C - C - H
| | | | | | | |
H H H H H H H H
|
Fuel, gasoline |
| Nonane | C₉H₂₀ |
H H H H H H H H H
| | | | | | | | |
H - C - C - C - C - C - C - C - C - C - H
| | | | | | | | |
H H H H H H H H H
|
Jet fuel, diesel |
| Decane | C₁₀H₂₂ |
H H H H H H H H H H
| | | | | | | | | |
H - C - C - C - C - C - C - C - C - C - C - H
| | | | | | | | | |
H H H H H H H H H H
|
Diesel fuel |
Solution 2: Simple and Understandable Answer
Alkanes are simple hydrocarbons made of carbon (C) and hydrogen (H) atoms, connected only by single bonds.
Example: Methane (CH₄) is the simplest alkane, found in natural gas.
H
|
H - C - H
|
H
Other Examples of Alkanes:
- Ethane (C₂H₆): Found in LPG gas.
- Propane (C₃H₈): Used in cooking and heating.
- Butane (C₄H₁₀): Used in lighters and LPG.
- Octane (C₈H₁₈): Found in petrol for vehicles.
Alkanes are important fuels used in households and industries.
Explain the following term with an example: Unsaturated Hydrocarbon
Solution 1: Scientific and Written Exam Answer
Unsaturated hydrocarbons are organic compounds that contain at least one double bond (alkenes) or one triple bond (alkynes) between carbon atoms in their molecular structure.
These hydrocarbons do not have the maximum number of hydrogen atoms due to the presence of multiple bonds.
Types of Unsaturated Hydrocarbons:
- Alkenes: Hydrocarbons containing at least one double bond (C=C).
- Alkynes: Hydrocarbons containing at least one triple bond (C≡C).
General Formula:
- Alkenes: $$ C_nH_{2n} $$
- Alkynes: $$ C_nH_{2n-2} $$
Example:
- Ethene (C₂H₄) → $$ H_2C=CH_2 $$
- Ethyne (C₂H₂) → $$ HC≡CH $$
Unsaturated hydrocarbons are more reactive than saturated hydrocarbons due to the presence of π-bonds, which are more accessible for chemical reactions.
Solution 2: Simple and Understandable Answer
Unsaturated hydrocarbons are compounds made up of carbon (C) and hydrogen (H) atoms but contain double or triple bonds between carbon atoms.
Types:
- Alkenes: Have at least one double bond (C=C).
- Alkynes: Have at least one triple bond (C≡C).
Simple Formula:
- Alkenes: $$ C_nH_{2n} $$
- Alkynes: $$ C_nH_{2n-2} $$
Example:
- Ethene (C₂H₄) → Used in ripening fruits.
- Ethyne (C₂H₂) → Used in welding.
Since unsaturated hydrocarbons have double or triple bonds, they are more reactive than single-bonded hydrocarbons (alkanes).
Explain the following term with an example: Homopolymer
Solution 1: Scientific and Written Exam Answer
A homopolymer is a type of polymer that is formed by the polymerization of only one type of monomer unit. The repeating structural unit in a homopolymer consists of the same monomer throughout the polymer chain.
General Formula: $$ (-M-)_n $$
Example:
- Polyethylene (PE): Formed from the monomer ethene (C₂H₄).
- Reaction: $$ n CH_2=CH_2 \rightarrow (-CH_2-CH_2-)_n $$
Homopolymers exhibit uniform properties since they consist of only one type of repeating unit.
Solution 2: Simple and Understandable Answer
A homopolymer is a polymer made from only one type of monomer. It means the same unit repeats again and again in the polymer chain.
Example:
- Polyethylene (PE): Made from ethene (C₂H₄), used in plastic bags and bottles.
Homopolymers are strong and useful in making plastic products like bottles, ropes, and packaging materials.
Explain the following term with an example: Monomer
Solution 1: Scientific and Written Exam Answer
A monomer is a small molecule that can chemically bond with other identical molecules to form a long-chain polymer. Monomers are the fundamental building blocks of polymers.
General Formula: $$ n(M) \rightarrow (-M-)_n $$
Example:
- Ethene (C₂H₄): A monomer that polymerizes to form polyethylene (PE).
- Reaction: $$ n CH_2=CH_2 \rightarrow (-CH_2-CH_2-)_n $$
Monomers undergo polymerization through different mechanisms like addition and condensation polymerization.
Solution 2: Simple and Understandable Answer
A monomer is a small unit that joins together to form a long-chain substance called a polymer.
Example:
- Ethene (C₂H₄): This small molecule combines with others to make plastic materials like polythene bags.
Monomers are like building blocks used to make large plastic and fiber materials.
Explain the following term with an example: Reduction
Solution 1: Scientific and Written Exam Answer
Reduction is a chemical reaction in which a substance gains electrons or undergoes a decrease in oxidation state. It can also be defined as the addition of hydrogen or the removal of oxygen from a compound.
General Representation:
$$ A + e^- \rightarrow A^- $$
Example:
- Reduction of copper oxide:
$$ CuO + H_2 \rightarrow Cu + H_2O $$
Here, copper oxide (CuO) loses oxygen and is reduced to copper (Cu).
Reduction always occurs together with oxidation in a redox reaction.
Solution 2: Simple and Understandable Answer
Reduction is a process in which oxygen is removed from a substance, or hydrogen is added to it.
Example:
- Reduction of iron oxide:
$$ Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2 $$
Here, iron oxide (Fe₂O₃) loses oxygen and gets reduced to iron (Fe).
Explain the following term with an example: Oxidant
Solution 1: Scientific and Written Exam Answer
An oxidant, also known as an oxidizing agent, is a substance that facilitates oxidation by accepting electrons from another substance. During this process, the oxidant itself undergoes reduction.
General Representation:
$$ Oxidant + e^- \rightarrow Reduced \ Form $$
Example:
- Oxygen as an oxidant:
$$ 2Mg + O_2 \rightarrow 2MgO $$
Here, oxygen (O₂) acts as an oxidant by gaining electrons and oxidizing magnesium (Mg) to magnesium oxide (MgO).
Oxidants play a crucial role in redox reactions, combustion, and various industrial processes.
Solution 2: Simple and Understandable Answer
An oxidant is a substance that helps in oxidation by taking electrons from another substance.
Example:
- Rusting of iron:
$$ 4Fe + 3O_2 + 6H_2O \rightarrow 4Fe(OH)_3 $$
Here, oxygen (O₂) is the oxidant as it removes electrons from iron (Fe), causing rusting.
Write the IUPAC name of the following structural formula: CH₃-CH₂-CH₂-CH₃
Solution 1: Scientific and Written Exam Answer
The given structural formula represents a straight-chain hydrocarbon with four carbon (C) atoms and single bonds between them. Since it belongs to the alkane family, its IUPAC name is derived from the prefix "but-" (for four carbon atoms) and the suffix "-ane" (for single bonds).
IUPAC Name: Butane
Structural Formula:
CH₃ - CH₂ - CH₂ - CH₃
Since there are no branches or functional groups, the name remains butane.
Solution 2: Simple and Understandable Answer
The given compound consists of four carbon (C) atoms connected in a straight chain with only single bonds. This type of compound is called an alkane, and the name for a four-carbon alkane is butane.
Final Answer: Butane
Example: Butane is commonly used as a fuel in lighters and gas cylinders.
Write the IUPAC name of the following structural formula: CH₃-CHOH-CH₃
Solution 1: Scientific and Written Exam Answer
The given structural formula consists of three carbon (C) atoms, an -OH (hydroxyl) functional group, and single bonds between all atoms. The hydroxyl (-OH) group indicates that the compound belongs to the alcohol family.
Step-by-Step IUPAC Naming:
- Identify the longest carbon chain: Three carbon atoms → "prop-".
- Since it is an alcohol (-OH group present), use the suffix "-ol".
- Number the chain so that the -OH group gets the lowest possible number: The -OH is attached to carbon 2.
IUPAC Name: Propan-2-ol
Structural Formula:
CH₃ - CHOH - CH₃
This compound is also known as isopropanol or isopropyl alcohol.
Solution 2: Simple and Understandable Answer
This compound is an alcohol because it has an -OH (hydroxyl) group attached to the second carbon in a three-carbon chain.
The correct name is: Propan-2-ol
Example: Propan-2-ol (Isopropyl alcohol) is commonly used as a disinfectant and hand sanitizer.
Write the IUPAC name of the following structural formula: CH₃-CH₂-COOH
Solution 1: Scientific and Written Exam Answer
The given structural formula consists of three carbon (C) atoms, a carboxyl (-COOH) functional group, and single bonds between all atoms. The presence of the -COOH group classifies it as a carboxylic acid.
Step-by-Step IUPAC Naming:
- Identify the longest carbon chain: Three carbon atoms → "prop-".
- The -COOH (carboxyl) group gives the suffix "-oic acid".
- The carboxyl (-COOH) group is always given position 1, so no number is needed.
IUPAC Name: Propanoic acid
Structural Formula:
CH₃ - CH₂ - COOH
It is also known as propionic acid, commonly found in food preservatives.
Solution 2: Simple and Understandable Answer
This compound is a carboxylic acid because it has a -COOH (carboxyl) group attached to a three-carbon chain.
The correct name is: Propanoic acid
Example: Propanoic acid is used as a preservative in bread and dairy products to prevent mold growth.
Write the IUPAC name of the following structural formula: CH₃-CH₂-NH₂
Solution 1: Scientific and Written Exam Answer
The given structural formula consists of two carbon (C) atoms and an -NH₂ (amine) functional group. The presence of the -NH₂ group classifies it as an amine.
Step-by-Step IUPAC Naming:
- Identify the longest carbon chain: Two carbon atoms → "eth-".
- The -NH₂ (amine) group gives the suffix "-amine".
- The amine group (-NH₂) is attached to the first carbon.
IUPAC Name: Ethanamine
Structural Formula:
CH₃ - CH₂ - NH₂
It is also commonly known as ethylamine, used in the pharmaceutical and dye industries.
Solution 2: Simple and Understandable Answer
This compound has two carbon atoms and an -NH₂ (amine) group, which makes it an amine.
The correct name is: Ethanamine
Example: Ethanamine is used in making medicines, plastics, and dyes.
Write the IUPAC name of the following structural formula: CH₃-CHO
Solution 1: Scientific and Written Exam Answer
The given structural formula consists of a -CHO (aldehyde) functional group attached to a single carbon chain.
Step-by-Step IUPAC Naming:
- The longest carbon chain contains two carbon (C) atoms, so the parent name is "eth-".
- The presence of the aldehyde (-CHO) group gives the suffix "-al".
IUPAC Name: Ethanal
Structural Formula:
CH₃ - CHO
It is commonly known as acetaldehyde, which is widely used in the production of acetic acid and perfumes.
Solution 2: Simple and Understandable Answer
This compound has two carbon atoms and contains the -CHO (aldehyde) group.
The correct name is: Ethanal
Example: Ethanal (Acetaldehyde) is used in making vinegar and perfumes.
Write the IUPAC name of the following structural formula: CH₃-CO-CH₂-CH₃
Solution 1: Scientific and Written Exam Answer
The given structural formula contains a carbonyl (-CO) functional group attached to carbon atoms on both sides, indicating it is a ketone.
Step-by-Step IUPAC Naming:
- The longest carbon chain has four (C₄) carbon atoms, so the parent name is "but-".
- The carbonyl (-CO) group is present at the second carbon, so the suffix "-one" is added.
- The position of the ketone group must be mentioned, so the name becomes butan-2-one.
IUPAC Name: Butan-2-one
Structural Formula:
CH₃ - CO - CH₂ - CH₃
It is also commonly known as Methyl Ethyl Ketone (MEK), which is used as a solvent in industries.
Solution 2: Simple and Understandable Answer
This compound has four carbon atoms and contains the -CO (ketone) functional group at the second carbon.
The correct name is: Butan-2-one
Example: Butan-2-one (MEK) is used in making paint, varnishes, and adhesives.
Identify the type of the following reaction of a carbon compound:
Reaction:
CH₃ - CH₂ - CH₂ - OH → CH₃ - CH₂ - COOH
Solution 1: Scientific and Written Exam Answer
This reaction involves the conversion of a primary alcohol (-OH) into a carboxylic acid (-COOH).
Type of Reaction: Oxidation Reaction
Explanation:
- The hydroxyl (-OH) functional group of propanol (CH₃-CH₂-CH₂-OH) is oxidized to form propanoic acid (CH₃-CH₂-COOH).
- Oxidizing agents like acidified potassium dichromate (K₂Cr₂O₇) or alkaline potassium permanganate (KMnO₄) help in this transformation.
Balanced Chemical Equation:
$$ CH₃ - CH₂ - CH₂ - OH + [O] \rightarrow CH₃ - CH₂ - COOH $$
Solution 2: Simple and Understandable Answer
In this reaction, alcohol (propanol) is changed into an acid (propanoic acid) by adding oxygen.
Type of Reaction: Oxidation Reaction
Example: This type of reaction happens when fruits like apples turn brown due to oxidation.
Identify the type of the following reaction of a carbon compound.
Reaction Given:
$$ CH_3 - CH_2 - CH_3 \rightarrow 3CO_2 + 4H_2O $$
Solution 1: Scientific and Written Exam Answer
The given reaction represents a combustion reaction. A combustion reaction occurs when a hydrocarbon reacts with oxygen to produce carbon dioxide and water.
Explanation:
- The reactant, propane $$ (CH_3 - CH_2 - CH_3 )$$, undergoes complete combustion in the presence of oxygen.
- It produces carbon dioxide $$( CO_2 )$$ and water $$( H_2O )$$ as the final products.
- Combustion reactions are highly exothermic, releasing heat energy.
Balanced Chemical Equation:
$$ C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O $$
This reaction is essential in various applications such as fuel combustion in engines and domestic gas burners.
Solution 2: Simple and Understandable Answer
This reaction is called a combustion reaction because propane $$ (CH_3 - CH_2 - CH_3 )$$ burns in oxygen to produce carbon dioxide $$( CO_2 )$$ and water $$( H_2O )$$.
Example in Daily Life:
- When LPG (Liquefied Petroleum Gas) is used in a kitchen stove, it undergoes combustion, similar to this reaction.
Such reactions release heat, which is why combustion is used for cooking, heating, and running vehicles.
Identify the type of the following reaction of a carbon compound.
Reaction Given:
$$ (CH_3 - CH = CH - CH_3) + Br_2 \rightarrow (CH_3 - CHBr - CHBr - CH_3) $$
Solution 1: Scientific and Written Exam Answer
The given reaction is an example of an electrophilic addition reaction. In this reaction, bromine ($$ Br_2 $$) is added across the double bond of butene, converting it into a dibromo compound.
Explanation:
- The reactant, butene $$ (CH_3 - CH = CH - CH_3) $$, contains a double bond, which is a site of high electron density.
- Bromine $$ (Br_2) $$ undergoes an electrophilic attack on the double bond, leading to its addition.
- The double bond is broken, and each carbon of the original double bond gains a bromine atom.
Reaction Mechanism:
$$ (CH_3 - CH = CH - CH_3) + Br_2 \rightarrow (CH_3 - CHBr - CHBr - CH_3) $$
This type of reaction is commonly observed in alkenes when they react with halogens.
Solution 2: Simple and Understandable Answer
This reaction is called an addition reaction because bromine $$ (Br_2) $$ is added to butene $$ (CH_3 - CH = CH - CH_3) $$, breaking its double bond and forming a single-bonded compound with two bromine atoms.
Example in Daily Life:
- When testing for unsaturation in vegetable oils, bromine water is used. If the oil contains double bonds (unsaturated compounds), bromine gets added, and the solution decolorizes.
Addition reactions are useful in chemical industries for making various organic compounds.
Identify the type of the following reaction of a carbon compound.
Reaction Given:
$$ (CH_3 - CH_3) + Cl_2 \rightarrow (CH_3 - CH_2 - Cl) + HCl $$
Solution 1: Scientific and Written Exam Answer
The given reaction is an example of a substitution reaction, specifically a free radical substitution reaction. This occurs when a hydrogen atom in an alkane ($$ CH_3 - CH_3 $$) is replaced by a chlorine ($$ Cl_2 $$) atom under the influence of ultraviolet (UV) light.
Explanation:
- The reaction takes place in the presence of UV light or sunlight, which helps in breaking the chlorine molecule ($$ Cl_2 $$) into free radicals.
- The highly reactive chlorine radical ($$ Cl^\cdot $$) attacks the ethane molecule ($$ CH_3 - CH_3 $$) and replaces one hydrogen atom with chlorine.
- This results in the formation of chloroethane ($$ CH_3 - CH_2 - Cl $$) and hydrogen chloride ($$ HCl $$).
Reaction Mechanism:
$$ (CH_3 - CH_3) + Cl_2 \xrightarrow{UV\ light} (CH_3 - CH_2 - Cl) + HCl $$
This type of reaction is characteristic of alkanes, where halogens replace hydrogen atoms.
Solution 2: Simple and Understandable Answer
This is a substitution reaction where one hydrogen atom in ethane ($$ CH_3 - CH_3 $$) is replaced by chlorine ($$ Cl_2 $$). This happens when the reaction is exposed to UV light.
Example in Daily Life:
- This reaction is similar to how chlorine is used in swimming pools to kill bacteria by replacing harmful substances.
- It is also used in the production of household disinfectants and chemicals.
Substitution reactions help in making various useful chemicals, such as solvents and medicines.
Identify the type of the following reaction of a carbon compound.
Reaction Given:
$$ (CH_3 - CH_2 - CH_2 - CH_2 - OH) \rightarrow (CH_3 - CH_2 - CH = CH_2) + H_2O $$
Solution 1: Scientific and Written Exam Answer
The given reaction is an example of a dehydration reaction or elimination reaction. In this reaction, a water molecule ($$ H_2O $$) is removed from the alcohol compound ($$ CH_3 - CH_2 - CH_2 - CH_2 - OH $$), leading to the formation of an alkene ($$ CH_3 - CH_2 - CH = CH_2 $$).
Explanation:
- This reaction occurs in the presence of a strong acid catalyst, such as concentrated sulfuric acid ($$ H_2SO_4 $$) and heat.
- The hydroxyl (-OH) group and a hydrogen atom from an adjacent carbon are eliminated as a water molecule ($$ H_2O $$), resulting in the formation of a double bond (alkene).
- Thus, butan-1-ol ($$ CH_3 - CH_2 - CH_2 - CH_2 - OH $$) is converted into but-1-ene ($$ CH_3 - CH_2 - CH = CH_2 $$).
Reaction Mechanism:
$$ (CH_3 - CH_2 - CH_2 - CH_2 - OH) \xrightarrow{H_2SO_4,\ heat} (CH_3 - CH_2 - CH = CH_2) + H_2O $$
Dehydration reactions are commonly used in organic synthesis to prepare alkenes.
Solution 2: Simple and Understandable Answer
This reaction is called a dehydration reaction because a water molecule ($$ H_2O $$) is removed from the alcohol compound.
How It Works:
- The compound butan-1-ol ($$ CH_3 - CH_2 - CH_2 - CH_2 - OH $$) loses a water molecule when heated with an acid.
- This results in the formation of but-1-ene ($$ CH_3 - CH_2 - CH = CH_2 $$), which is an alkene (a compound with a double bond).
Example in Daily Life:
- This process is similar to removing water from fruit juice to make fruit concentrates.
- In industries, dehydration reactions are used to make plastics and fuel from alcohols.
Thus, this reaction is an important method to convert alcohols into useful compounds like alkenes.
Identify the type of the following reaction of a carbon compound.
Reaction Given:
$$ (CH_3 - CH_2 - COOH) + NaOH \rightarrow (CH_3 - CH_2 - COO^- Na^+) + H_2O $$
Solution 1: Scientific and Written Exam Answer
The given reaction is an example of a neutralization reaction or acid-base reaction. In this reaction, ethanoic acid ($$ CH_3 - CH_2 - COOH $$) reacts with sodium hydroxide ($$ NaOH $$), a strong base, to form a sodium salt of carboxylic acid ($$ CH_3 - CH_2 - COO^- Na^+ $$) and water ($$ H_2O $$).
Explanation:
- Carboxylic acids ($$ -COOH $$) are acidic in nature and react with bases like NaOH.
- The hydrogen ion (H⁺) from the carboxyl group ($$ -COOH $$) combines with the hydroxide ion (OH⁻) from NaOH to form water ($$ H_2O $$).
- The remaining part of the acid forms a carboxylate salt ($$ CH_3 - CH_2 - COO^- Na^+ $$).
General Neutralization Reaction Formula:
$$ \text{Acid} + \text{Base} \rightarrow \text{Salt} + \text{Water} $$
This type of reaction is used in the preparation of soaps and detergents, where fatty acids react with bases to form soap.
Solution 2: Simple and Understandable Answer
This reaction is called a neutralization reaction because an acid ($$ CH_3 - CH_2 - COOH $$) reacts with a base ($$ NaOH $$) to form a salt ($$ CH_3 - CH_2 - COO^- Na^+ $$) and water ($$ H_2O $$).
How It Works:
- Carboxylic acids like propanoic acid ($$ CH_3 - CH_2 - COOH $$) are weak acids.
- When mixed with a strong base like NaOH, the acid loses H⁺ (hydrogen ion), and NaOH donates OH⁻ (hydroxide ion).
- They combine to form water ($$ H_2O $$), leaving behind a sodium salt ($$ CH_3 - CH_2 - COO^- Na^+ $$).
Example in Daily Life:
- Antacids work in a similar way. When we have acidity, we take an antacid (a base), which neutralizes stomach acid.
- Soap formation also involves similar reactions where fatty acids react with sodium hydroxide to form soap.
Thus, this reaction is a fundamental example of an acid-base neutralization.
Identify the type of the following reaction of a carbon compound.
Reaction Given:
$$ (CH_3 - COOH) + (CH_3 - OH) \rightarrow (CH_3 - COO - CH_3) + H_2O $$
Solution 1: Scientific and Written Exam Answer
The given reaction is classified as an esterification reaction. In this reaction, acetic acid (CH₃COOH) reacts with methanol (CH₃OH) in the presence of an acidic catalyst, typically concentrated sulfuric acid (H₂SO₄), to form methyl acetate (CH₃COOCH₃) and water (H₂O).
Explanation:
- Carboxylic acids (-COOH) react with alcohols (-OH) to form esters (-COO-R) and water.
- This reaction requires a strong acid catalyst such as concentrated sulfuric acid (H₂SO₄).
- It is a slow and reversible reaction used in organic synthesis for perfumes, flavoring agents, and industrial applications.
General Esterification Reaction Formula:
$$ \text{Carboxylic Acid} + \text{Alcohol} \rightarrow \text{Ester} + \text{Water} $$
Esters are widely used in perfumes, cosmetics, and food flavoring due to their pleasant fruity aroma.
Solution 2: Simple and Understandable Answer
This reaction is called an esterification reaction because an acid (CH₃COOH, acetic acid) reacts with an alcohol (CH₃OH, methanol) to form an ester (CH₃COOCH₃, methyl acetate) and water (H₂O).
How It Works:
- Acetic acid (commonly found in vinegar) reacts with alcohol.
- When sulfuric acid (H₂SO₄) is added, the reaction forms a sweet-smelling ester.
- Water (H₂O) is produced as a byproduct.
Example in Daily Life:
- Esterification is used in making perfumes and food flavoring agents.
- Esters have fruity scents found in bananas, apples, and strawberries.
Thus, this reaction is important in industries that manufacture flavors and fragrances.
Write structural formulae for the following IUPAC name.
Given Compound: Pent-2-one
Solution 1: Scientific and Written Exam Answer
Pent-2-one is a ketone with a five-carbon chain, where the carbonyl group (C=O) is positioned at the second carbon.
Structural Formula:
$$ CH_3 - CO - CH_2 - CH_2 - CH_3 $$
Explanation:
- The name "Pent-2-one" indicates a five-carbon (pent-) chain.
- The suffix "-one" refers to the presence of a ketone functional group (-CO-).
- The number "2" specifies the location of the carbonyl group (C=O) at the second carbon.
- Ketones always have the carbonyl group bonded to two carbon atoms.
Expanded Structural Formula:
$$ CH_3 - C(=O) - CH_2 - CH_2 - CH_3 $$
Pent-2-one is commonly found in organic synthesis and is used in industrial applications such as solvent production.
Solution 2: Simple and Understandable Answer
Pent-2-one is a type of compound called a ketone. It has five carbon (C) atoms in a straight chain, and an oxygen (O) atom double-bonded to the second carbon.
Simple Structural Formula:
$$ CH_3 - CO - CH_2 - CH_2 - CH_3 $$
How It Works:
- "Pent" means the compound has five carbon atoms.
- "-one" means it contains a ketone (-C
Exercises | Q 7.2 | Page 134
Write structural formulae for the following IUPAC name.
Given Compound: 2-Chlorobutane
Solution 1: Scientific and Written Exam Answer
2-Chlorobutane is a haloalkane where a chlorine (Cl) atom is attached to the second carbon of a four-carbon straight-chain alkane (butane).
Structural Formula:
$$ CH_3 - CH(Cl) - CH_2 - CH_3 $$
Explanation:
- "But" refers to a four-carbon (C₄) chain.
- "Ane" means it is a saturated alkane (single bonds only).
- "2-Chloro" indicates that a chlorine (Cl) atom is attached to the second carbon.
Expanded Structural Formula:
$$ CH_3 - CH(Cl) - CH_2 - CH_3 $$
2-Chlorobutane is commonly used in organic synthesis and is an intermediate in the production of pharmaceuticals and industrial chemicals.
Solution 2: Simple and Understandable Answer
2-Chlorobutane is a halogen-substituted hydrocarbon. It has four carbon (C) atoms, and a chlorine (Cl) atom is attached to the second carbon.
Simple Structural Formula:
$$ CH_3 - CH(Cl) - CH_2 - CH_3 $$
How It Works:
- "Butane" means the compound has four carbon atoms.
- "Chloro" means one hydrogen (H) is replaced by chlorine (Cl).
- "2" means the chlorine is attached to the second carbon.
Example in Daily Life:
- Halogenated hydrocarbons like 2-chlorobutane are used in the chemical and pharmaceutical industries.
- They are also used in the production of solvents and intermediates in organic chemistry.
Thus, 2-chlorobutane is an organic compound where a chlorine atom replaces a hydrogen atom on the second carbon of butane.
Exercises | Q 7.3 | Page 134
Write structural formulae for the following IUPAC name.
Given Compound: Propan-2-ol
Solution 1: Scientific and Written Exam Answer
Propan-2-ol, also known as isopropanol or isopropyl alcohol, is a type of alcohol in which a hydroxyl group (-OH) is attached to the second carbon of a three-carbon propane chain.
Structural Formula:
$$ CH_3 - CH(OH) - CH_3 $$
Explanation:
- "Prop" means the compound has three carbon (C) atoms.
- "Ane" indicates it is a saturated hydrocarbon (alkane with single bonds only).
- "2-ol" signifies the presence of a hydroxyl (-OH) group on the second carbon.
Expanded Structural Formula:
$$ CH_3 - CH(OH) - CH_3 $$
Propan-2-ol is a secondary alcohol, meaning the hydroxyl (-OH) group is attached to a carbon that is bonded to two other carbon atoms.
Uses:
- It is widely used as a disinfectant, antiseptic, and solvent in medical and industrial applications.
- It is a key ingredient in hand sanitizers, rubbing alcohol, and cleaning agents.
Solution 2: Simple and Understandable Answer
Propan-2-ol is a type of alcohol with three carbon atoms and a hydroxyl (-OH) group on the second carbon.
Simple Structural Formula:
$$ CH_3 - CH(OH) - CH_3 $$
How It Works:
- "Prop" means three carbon atoms (C₃).
- "Ol" means it is an alcohol (contains an -OH group).
- "2" means the -OH group is on the second carbon.
Example in Daily Life:
- Propan-2-ol is the main ingredient in hand sanitizers and rubbing alcohol.
- It is used for cleaning surfaces, removing ink stains, and as a medical disinfectant.
Thus, propan-2-ol is a secondary alcohol widely used in medical and industrial applications.
Exercises | Q 7.4 | Page 134
Write structural formulae for the following IUPAC name.
Given Compound: Methanal
Solution 1: Scientific and Written Exam Answer
Methanal, commonly known as formaldehyde, is the simplest aldehyde with the molecular formula CH₂O. It consists of a carbonyl functional group (-CHO) attached to a single hydrogen atom.
Structural Formula:
$$ H - C(=O) - H $$
Explanation:
- "Meth" means the compound contains one carbon (C) atom.
- "Anal" signifies the presence of an aldehyde (-CHO) functional group.
- Aldehydes always have the -CHO group at the end of the carbon chain.
Expanded Structural Formula:
$$ \text{H} - \text{C} (= \text{O}) - \text{H} $$
Methanal is a gas at room temperature and is widely used in industrial and laboratory applications.
Uses:
- It is used as a preservative in biological specimens.
- It is a key ingredient in resins, plastics, and adhesives.
- It is used as a disinfectant and sterilizing agent in hospitals and laboratories.
Solution 2: Simple and Understandable Answer
Methanal (formaldehyde) is the simplest aldehyde with the formula CH₂O. It has one carbon atom, a double-bonded oxygen (C=O), and two hydrogen atoms.
Simple Structural Formula:
$$ H - C(=O) - H $$
How It Works:
- "Meth" means one carbon atom (C₁).
- "Anal" means it has an aldehyde (-CHO) group.
- Aldehydes always have the -CHO group at the end of the molecule.
Example in Daily Life:
- Formaldehyde is used in preserving dead organisms in laboratories.
- It is found in household disinfectants and sterilizing agents.
Thus, methanal is a highly reactive aldehyde used in various industries.
Exercises | Q 7.5 | Page 134
Write structural formulae for the following IUPAC name.
Given Compound: Butanoic Acid
Solution 1: Scientific and Written Exam Answer
Butanoic acid, also known as butyric acid, is a carboxylic acid with the molecular formula C₄H₈O₂. It contains a carboxyl (-COOH) functional group attached to a four-carbon alkane chain.
Structural Formula:
$$ CH_3 - CH_2 - CH_2 - COOH $$
Explanation:
- The prefix "But" indicates four carbon (C₄) atoms.
- The suffix "oic acid" means the presence of a carboxyl (-COOH) functional group.
- Carboxylic acids always have the -COOH group at the end of the carbon chain.
Expanded Structural Formula:
$$ \text{CH}_3 - \text{CH}_2 - \text{CH}_2 - \text{COOH} $$
Butanoic acid has an unpleasant odor and is commonly found in rancid butter, dairy products, and animal fats.
Uses:
- It is used in the manufacture of perfumes, food additives, and pharmaceuticals.
- It serves as a precursor for esters, which are used in artificial flavors.
- It is an important fermentation byproduct in dairy products.
Solution 2: Simple and Understandable Answer
Butanoic acid (butyric acid) is a carboxylic acid with four carbon atoms and a -COOH functional group.
Simple Structural Formula:
$$ CH_3 - CH_2 - CH_2 - COOH $$
How It Works:
- "But" means four carbon atoms.
- "Oic acid" means it contains a -COOH carboxyl group.
- Carboxylic acids are always acidic and found in nature.
Example in Daily Life:
- Butanoic acid is found in butter, cheese, and dairy products.
- It has a strong, rancid smell but is used in perfumes and food flavorings.
Thus, butanoic acid is an important organic acid found in natural and industrial applications.
Exercises | Q 7.6 | Page 134
Write structural formulae for the following IUPAC name.
Given Compound: 1-Bromopropane
Solution 1: Scientific and Written Exam Answer
1-Bromopropane is a haloalkane with the molecular formula C₃H₇Br. It contains a bromine (Br) atom attached to the first carbon of a three-carbon propane chain.
Structural Formula:
$$ CH_3 - CH_2 - CH_2Br $$
Explanation:
- The prefix "Prop" indicates three carbon (C₃) atoms.
- The suffix "ane" means it is a saturated hydrocarbon (alkane).
- "1-Bromo" means that a bromine (Br) atom is attached to the first carbon in the chain.
Expanded Structural Formula:
$$ \text{CH}_3 - \text{CH}_2 - \text{CH}_2Br $$
Uses:
- Used as a solvent in adhesives, degreasing, and cleaning applications.
- Serves as an intermediate in organic synthesis.
- Used in the manufacture of pharmaceuticals and pesticides.
Solution 2: Simple and Understandable Answer
1-Bromopropane is a chemical compound that has three carbon atoms and one bromine (Br) atom attached to the first carbon.
Simple Structural Formula:
$$ CH_3 - CH_2 - CH_2Br $$
How It Works:
- "Prop" means three carbon atoms.
- "Ane" means it is a saturated hydrocarbon (alkane).
- "1-Bromo" means a bromine (Br) atom is attached to the first carbon.
Example in Daily Life:
- 1-Bromopropane is used as a cleaning solvent in industries.
- It is also used in chemical manufacturing and pharmaceuticals.
Thus, 1-Bromopropane is an important organic halogen compound used in various industries.
Exercises | Q 7.7 | Page 134
Write structural formulae for the following IUPAC name.
Given Compound: Ethanamine
Solution 1: Scientific and Written Exam Answer
Ethanamine (also known as Ethylamine) is an organic compound with the molecular formula C₂H₅NH₂. It belongs to the class of primary amines, where an amino group (-NH₂) is attached to an ethane (C₂H₆) chain.
Structural Formula:
$$ CH_3 - CH_2 - NH_2 $$
Explanation:
- The prefix "Eth" indicates two carbon (C₂) atoms.
- The suffix "amine" means it contains an amino group (-NH₂).
- Since the -NH₂ group is attached to the ethane chain, it forms Ethanamine.
Expanded Structural Formula:
$$ \text{H}_3\text{C} - \text{CH}_2 - \text{NH}_2 $$
Uses:
- Used in pharmaceuticals, dyes, and pesticides.
- Serves as a building block in organic synthesis.
- Used in rubber processing and fuel additives.
Solution 2: Simple and Understandable Answer
Ethanamine is a chemical compound that has two carbon (C) atoms and an -NH₂ (amino group) attached to the first carbon.
Simple Structural Formula:
$$ CH_3 - CH_2 - NH_2 $$
How It Works:
- "Eth" means two carbon atoms.
- "Ane" means it is a single-bonded hydrocarbon (alkane).
- "Amino (-NH₂)" means it is an amine group attached to the ethane chain.
Example in Daily Life:
- Used in pharmaceutical drugs and fertilizers.
- Used to make synthetic fibers, resins, and dyes.
Thus, Ethanamine is an important organic amine used in various industries.
Exercises | Q 7.8 | Page 134
Write structural formulae for the following IUPAC name.
Given Compound: Butanone
Solution 1: Scientific and Written Exam Answer
Butanone, also known as Methyl Ethyl Ketone (MEK), is an organic compound with the molecular formula C₄H₈O. It belongs to the ketone family, where a carbonyl group (C=O) is bonded to two alkyl groups.
Structural Formula:
$$ CH_3 - CO - CH_2 - CH_3 $$
Explanation:
- The prefix "But" indicates four carbon (C₄) atoms.
- The suffix "one" represents a ketone functional group (-CO-).
- The carbonyl group (C=O) is placed at the second carbon, making it butan-2-one.
Expanded Structural Formula:
$$ \text{CH}_3 - \text{CO} - \text{CH}_2 - \text{CH}_3 $$
Uses:
- Used as a solvent in paints, varnishes, and adhesives.
- Found in plastic and textile industries.
- Used in the production of pharmaceuticals and resins.
Solution 2: Simple and Understandable Answer
Butanone is a chemical that has four carbon atoms (C₄) and a ketone group (-CO-) at the second carbon.
Simple Structural Formula:
$$ CH_3 - CO - CH_2 - CH_3 $$
How It Works:
- "But" means four carbon atoms.
- "one" means there is a C=O (ketone) functional group.
- The C=O is at the second carbon, making it butan-2-one.
Example in Daily Life:
- Used in nail polish removers.
- Used as a solvent in printing inks and coatings.
Thus, Butanone is a useful solvent and industrial chemical.
Exercises | Q 8.1 | Page 134
Write answer as directed.
Question: What causes the existence of a very large number of carbon compounds?
Solution 1: Scientific and Written Exam Answer
The existence of a very large number of carbon compounds is mainly due to two fundamental properties of carbon (C):
1. Catenation
Carbon atoms can form strong covalent bonds with other carbon atoms, creating long chains, branched structures, and rings.
Example: Alkanes (C-C single bonds), Alkenes (C=C double bonds), and Alkynes (C≡C triple bonds).
2. Tetravalency
Carbon has four valence electrons (electronic configuration: 2,4), allowing it to form four stable covalent bonds with other elements such as hydrogen (H), oxygen (O), nitrogen (N), sulfur (S), and halogens.
Example: Methane (CH₄), Carbon Dioxide (CO₂), and Ethanol (C₂H₅OH).
3. Formation of Multiple Bonds
Carbon can form single, double, or triple bonds, leading to a variety of compounds.
Example: Ethane (C₂H₆) has a single bond, Ethene (C₂H₄) has a double bond, and Ethyne (C₂H₂) has a triple bond.
4. Isomerism
Carbon compounds exhibit structural and stereoisomerism, leading to a vast number of different molecules with the same molecular formula.
Example: Butane (C₄H₁₀) has two isomers – n-butane and iso-butane.
Conclusion:
Due to catenation, tetravalency, multiple bonding, and isomerism, carbon forms a vast variety of compounds, making it the foundation of organic chemistry.
Solution 2: Simple and Understandable Answer
Carbon forms a huge number of compounds because of these special properties:
- Catenation: Carbon atoms join together to form long chains and rings.
- Tetravalency: Carbon has 4 hands (valency of 4), so it can bond with many other atoms like H, O, N, Cl, etc.
- Strong Bonds: Carbon makes strong covalent bonds, keeping the compounds stable.
- Different Shapes: Carbon compounds exist in straight chains, branched chains, or rings, making them unique.
Example in Daily Life:
- Plastic (Polyethylene) is made of carbon chains.
- Fuels like petrol, diesel, and LPG contain carbon compounds.
- Our body is made of proteins, carbohydrates, and DNA, which are all carbon-based.
Thus, carbon compounds are found everywhere in our daily life!
Exercises | Q 8.2 | Page 134
Write answer as directed.
Question: Saturated hydrocarbons are classified into three types. Write these names giving one example each.
Solution 1: Scientific and Written Exam Answer
Saturated hydrocarbons, also known as alkanes, contain only single bonds (C-C) between carbon atoms and follow the general formula CₙH₂ₙ₊₂.
Types of Saturated Hydrocarbons:
- Straight-Chain Alkanes (Normal Alkanes):
- Branched-Chain Alkanes:
- Cyclic Alkanes (Cycloalkanes):
These alkanes have continuous, unbranched carbon chains.
Example: Methane (CH₄) – The simplest alkane, found in natural gas.
These alkanes have one or more side chains (alkyl groups) attached to the main carbon chain.
Example: Iso-butane (C₄H₁₀) – Used as a refrigerant and fuel.
These alkanes form ring structures instead of open chains.
Example: Cyclohexane (C₆H₁₂) – Found in petroleum and used as a solvent.
Conclusion: Alkanes exist as straight-chain, branched-chain, and cyclic structures, making them essential in fuels, lubricants, and industrial applications.
Solution 2: Simple and Understandable Answer
Saturated hydrocarbons (alkanes) contain only single bonds between carbon atoms.
Types of Saturated Hydrocarbons:
- 1. Straight-Chain Alkanes: Carbon atoms form a single, continuous line.
- 2. Branched-Chain Alkanes: Some carbon atoms branch out from the main chain.
- 3. Cyclic Alkanes: Carbon atoms form a closed ring.
Example: Methane (CH₄) – Found in cooking gas.
Example: Iso-butane (C₄H₁₀) – Used in LPG gas.
Example: Cyclohexane (C₆H₁₂) – Used in making plastics.
These hydrocarbons are found in fuels, oils, and waxes that we use daily.
Exercises | Q 8.3 | Page 134
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Question: Give any four functional groups containing oxygen as the heteroatom in it. Write name and structural formula of one example each.
Solution 1: Scientific and Written Exam Answer
Functional groups are specific groups of atoms within molecules that determine the chemical properties of organic compounds. The following are four functional groups that contain oxygen as the heteroatom:
Functional Group Name Example Structural Formula Hydroxyl (-OH) Alcohol Ethanol (C₂H₅OH) CH₃-CH₂-OH Carbonyl (>C=O) Aldehyde Ethanal (CH₃CHO) CH₃-CHO Carboxyl (-COOH) Carboxylic Acid Ethanoic Acid (CH₃COOH) CH₃-COOH Ester (-COO-) Esters Methyl Ethanoate (CH₃COOCH₃) CH₃-COO-CH₃ Conclusion: These functional groups containing oxygen significantly influence the properties of organic compounds, making them essential in chemistry.
Solution 2: Simple and Understandable Answer
Certain groups of atoms give molecules their special properties. These are called functional groups. Here are four oxygen-containing functional groups:
- 1. Hydroxyl (-OH) → Alcohol
- 2. Carbonyl (>C=O) → Aldehyde
- 3. Carboxyl (-COOH) → Carboxylic Acid
- 4. Ester (-COO-) → Ester
Example: Ethanol (C₂H₅OH) – Found in alcoholic drinks.
Example: Ethanal (CH₃CHO) – Used in perfumes.
Example: Ethanoic Acid (CH₃COOH) – Found in vinegar.
Example: Methyl Ethanoate (CH₃COOCH₃) – Used in making perfumes.
These functional groups help in making alcohols, perfumes, and medicines.
Exercises | Q 8.4 | Page 134
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Question: Give names of three functional groups containing three different hetero atoms. Write name and structural formula of one example each.
Solution 1: Scientific and Written Exam Answer
Heteroatoms are atoms in an organic molecule that are not carbon or hydrogen. Below are three functional groups that contain different heteroatoms:
Functional Group Heteroatom Example Structural Formula Amino (-NH₂) Nitrogen (N) Ethanamine (C₂H₅NH₂) CH₃-CH₂-NH₂ Thiol (-SH) Sulfur (S) Ethane Thiol (C₂H₅SH) CH₃-CH₂-SH Halo (-Cl, -Br, -I) Halogen (Cl, Br, I) Chloromethane (CH₃Cl) CH₃-Cl Conclusion: These functional groups influence the chemical properties and reactivity of organic compounds.
Solution 2: Simple and Understandable Answer
Some groups in organic molecules contain elements other than carbon and hydrogen. These are called functional groups with heteroatoms. Here are three examples:
- 1. Amino (-NH₂) → Contains Nitrogen
- 2. Thiol (-SH) → Contains Sulfur
- 3. Halo (-Cl, -Br, -I) → Contains Halogen
Example: Ethanamine (C₂H₅NH₂) – Found in medicines.
Example: Ethane Thiol (C₂H₅SH) – Used in making rubber.
Example: Chloromethane (CH₃Cl) – Used as a refrigerant.
These functional groups are important in making medicines, plastics, and perfumes.
Exercises | Q 8.5 | Page 134
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Question: Give names of three natural polymers. Write the place of their occurrence and names of monomers from which they are formed.
Solution 1: Scientific and Written Exam Answer
A polymer is a large molecule composed of repeated subunits called monomers. Natural polymers occur in living organisms and are essential for life processes.
Natural Polymer Place of Occurrence Monomer Units 1. Cellulose Plants (Cell Walls of Plant Cells) β-D-Glucose 2. Proteins Animals and Plants (Muscles, Enzymes, Hair, Skin) Amino Acids 3. Natural Rubber Rubber Trees (Latex Sap) Isoprene (2-Methyl-1,3-Butadiene) Conclusion: Natural polymers play crucial roles in biological structures, metabolism, and industrial applications.
Solution 2: Simple and Understandable Answer
Polymers are long-chain molecules made up of small repeating units (monomers). Nature provides many important polymers. Here are three examples:
- 1. Cellulose: Found in plant cell walls, made of glucose. Used in making paper and textiles.
- 2. Proteins: Found in animals and plants, made of amino acids. Helps in body growth and repair.
- 3. Natural Rubber: Comes from rubber tree latex, made of isoprene. Used in making tires and gloves.
Natural polymers are important for life and industry, making our world more functional and sustainable.
Exercises | Q 8.6 | Page 134
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Question: What is meant by vinegar and gasohol? What are their uses?
Solution 1: Scientific and Written Exam Answer
Vinegar: Vinegar is a dilute solution of acetic acid (CH₃COOH) in water, typically containing 4-8% acetic acid.
Uses of Vinegar:
- Used as a food preservative and flavoring agent in cooking.
- Acts as a natural cleaning agent due to its antibacterial properties.
- Used in the food industry for making pickles and sauces.
Gasohol: Gasohol is a fuel mixture of gasoline and ethanol (C₂H₅OH), commonly containing 10% ethanol and 90% gasoline.
Uses of Gasohol:
- Used as an alternative fuel in vehicles to reduce pollution.
- Enhances fuel efficiency and reduces dependence on fossil fuels.
- Helps in reducing carbon monoxide emissions, making it environmentally friendly.
Solution 2: Simple and Understandable Answer
Vinegar: A liquid made from acetic acid and water. It is commonly used in cooking, cleaning, and food preservation.
Simple Uses of Vinegar:
- Used in salads and pickles to add sour taste.
- Helps to remove stains and kill bacteria at home.
Gasohol: A fuel made by mixing ethanol with petrol. It helps to save fuel and reduce pollution.
Simple Uses of Gasohol:
- Used in cars and bikes as a clean fuel.
- Reduces harmful gases from vehicle exhaust.
Conclusion: Vinegar is useful in food and cleaning, while gasohol is an eco-friendly fuel for vehicles.
Exercises | Q 8.7 | Page 134
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Question: What is a catalyst? Write any one reaction which is brought about by the use of a catalyst.
Solution 1: Scientific and Written Exam Answer
A catalyst is a substance that increases the rate of a chemical reaction without undergoing any permanent chemical change itself.
Example of a Catalytic Reaction:
The decomposition of hydrogen peroxide (H₂O₂) into water (H₂O) and oxygen (O₂) in the presence of the catalyst manganese dioxide (MnO₂):
2H₂O₂ → 2H₂O + O₂ (in presence of MnO₂)
Here, MnO₂ acts as a catalyst, speeding up the reaction without being consumed.
Solution 2: Simple and Understandable Answer
A catalyst is a helper in a reaction. It makes the reaction faster but does not change itself.
Simple Example:
Hydrogen peroxide (H₂O₂) breaks down into water and oxygen with the help of MnO₂.
Reaction: H₂O₂ → H₂O + O₂ (with MnO₂)
📌 Easy to Remember: A catalyst is like a teacher who helps students learn faster but stays the same! 😊