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Class 10 · Science · Chapter 4

Carbon and its Compounds

An interactive, concept-first guide to bonding, chains, functional groups, and cleansing action designed for CBSE 2026 board preparation. Carbon और उसके compounds के bonding, chains, functional groups, और cleansing action को आसानी से समझाने वाला एक interactive guide, जो CBSE 2026 board preparation के लिए designed है।

1. Bonding in Carbon — The Covalent Bond कार्बन में आबंधन — सहसंयोजी आबंध

Goal: Understand why carbon forms covalent bonds by sharing electrons rather than losing or gaining them, and visualize sharing in simple molecules. Goal: यह समझें कि carbon electrons lose या gain करने के बजाय उन्हें share करके covalent bonds क्यों बनाता है, और simple molecules में sharing को visualize करें।

Carbon is the element that forms the basis of all life-forms and many things we use daily. In the earth's crust, carbon is present in a tiny amount of only 0.02% (in minerals like carbonates, coal, and petroleum), and the atmosphere has 0.03% of carbon dioxide gas [NCERT p.58]. Despite this minute amount, the chemistry of carbon is vast. Carbon वो element है जो सभी life-forms और हमारी daily-life की बहुत सी चीजों का basis बनाता है। Earth's crust में carbon सिर्फ 0.02% जैसी बहुत कम मात्रा में (carbonates, coal, और petroleum जैसे minerals के रूप में) present है, और atmosphere में सिर्फ 0.03% carbon dioxide gas है [NCERT p.58]। इतनी कम amount में होने के बावजूद, carbon की chemistry बहुत vast (विशाल) है।

The Octet Rule and Carbon's Dilemma Octet Rule और Carbon की दुविधा

The atomic number of carbon is 6. Its electronic configuration is 2, 4, meaning it has 4 valence electrons in its outermost shell (L-shell) [NCERT p.58]. To attain a noble gas configuration (an octet of 8 electrons), carbon needs to either gain 4 electrons or lose 4 electrons. However, both pathways are highly unfavorable energy-wise: Carbon का atomic number 6 है। इसका electronic configuration 2, 4 है, जिसका मतलब है कि इसके outermost shell (L-shell) में 4 valence electrons होते हैं [NCERT p.58]। Noble gas configuration (यानी 8 electrons का octet) पाने के लिए, carbon को या तो 4 electrons gain करने होंगे या फिर 4 electrons lose करने होंगे। लेकिन, energy के हिसाब से ये दोनों ही तरीके बहुत unfavorable (मुश्किल) हैं:

Path A (Gaining 4 electrons to form C⁴⁻ anion): It would be extremely difficult for the nucleus with 6 protons to hold onto 10 electrons (6 protons + 10 electrons), causing massive electrostatic repulsion [NCERT p.59]. Path A (C⁴⁻ anion बनाने के लिए 4 electrons gain करना): 6 protons वाले nucleus के लिए 10 electrons (6 protons + 10 electrons) को hold करके रखना बहुत मुश्किल होगा, क्योंकि इससे बहुत ज्यादा electrostatic repulsion होगा [NCERT p.59]।
Path B (Losing 4 electrons to form C⁴⁺ cation): It would require a huge amount of energy to remove 4 electrons sequentially, leaving behind a carbon cation with 6 protons holding onto just 2 remaining electrons [NCERT p.59]. Path B (C⁴⁺ cation बनाने के लिए 4 electrons lose करना): 4 electrons को एक-एक करके remove करने के लिए बहुत ज्यादा energy की जरूरत होगी, जिससे 6 protons वाला carbon cation सिर्फ 2 electrons को ही hold कर पाएगा [NCERT p.59]।

Remember: Carbon overcomes this energy hurdle not by losing or gaining electrons, but by sharing its valence electrons with other carbon atoms or with atoms of other elements. This bond formed by sharing electron pairs is called a covalent bond [NCERT p.59]. Carbon इस energy hurdle (रुकावट) को electrons lose या gain करके नहीं, बल्कि अपने valence electrons को दूसरे carbon atoms या दूसरे elements के atoms के साथ share करके पार करता है। Electrons की sharing से बनने वाले इस bond को covalent bond कहते हैं [NCERT p.59]।

Covalent Sharing in Simple Molecules Simple Molecules में Covalent Sharing

Before diving into carbon, let us examine electron sharing in simpler molecules using the Covalent Orbit Sharing Visualizer below: Carbon के बारे में गहराई से जानने से पहले, नीचे दिए गए Covalent Orbit Sharing Visualizer से simple molecules में electron sharing को समझते हैं:

Covalent Orbit Sharing Visualizer

Classroom Analogy: Sharing a Textbook Imagine two students sitting next to each other, and each needs a textbook to study. Instead of buying two books (transferring ownership), they place one textbook in the middle of their shared desk. Both can read it simultaneously. In a covalent bond, the shared electrons belong to both atomic nuclei at the same time! सोचो दो students पास-पास बैठे हैं और दोनों को पढ़ने के लिए एक textbook की जरूरत है। दो अलग किताबें खरीदने के बजाय, वे एक ही textbook को अपने shared desk के बीच में रख लेते हैं। अब दोनों इसे एक साथ पढ़ सकते हैं। Covalent bond में भी, shared electrons दोनों atomic nuclei से एक ही समय पर belong करते हैं!

Allotropes of Carbon Allotropes of Carbon (कार्बन के अपररूप)

Carbon exists in different physical forms in nature, known as allotropes. Their physical properties differ greatly because of the way the carbon atoms are bonded together, although their chemical properties are identical [NCERT p.59]: Nature में carbon अलग-अलग physical forms में मिलता है, जिन्हें allotropes (अपररूप) कहते हैं। इनके bonding patterns अलग होने की वजह से इनकी physical properties में बहुत अंतर होता है, हालांकि इनकी chemical properties बिल्कुल identical (एक जैसी) होती हैं [NCERT p.59]:

Diamond (हीरा)

Each carbon is bonded to four other carbon atoms in a rigid, three-dimensional tetrahedral structure. This makes diamond the hardest known natural substance [NCERT p.59]. It is a non-conductor of electricity. इसमें हर carbon atom 4 दूसरे carbon atoms के साथ एक rigid, 3D tetrahedral structure में bonded रहता है। यही वजह है कि diamond सबसे hard natural substance है [NCERT p.59]। यह electricity का non-conductor (कुचालक) होता है।

Graphite (ग्रेफाइट)

Each carbon is bonded to three other carbon atoms in a hexagonal pattern, forming layers stacked on top of each other. The layers slide over one another, making it smooth and slippery. It conducts electricity due to free electrons [NCERT p.59]. इसमें हर carbon atom 3 दूसरे carbon atoms के साथ hexagonal pattern में bonded रहता है, जिससे एक के ऊपर एक stacked layers बनती हैं। ये layers एक-दूसरे के ऊपर slide कर सकती हैं, जिससे यह smooth और slippery (चिकना) हो जाता है। इसमें free electrons की वजह से electricity conduct होती है [NCERT p.59]।

Fullerene C-60 (फुलेरीन)

Carbon atoms are arranged in a spherical shape resembling a soccer ball. Since it looked like the geodesic dome designed by US architect Buckminster Fuller, it was named Buckminsterfullerene [NCERT p.60]. इसमें carbon atoms एक soccer ball की तरह spherical shape में arranged होते हैं। चूंकि यह US architect Buckminster Fuller द्वारा design किए गए geodesic dome जैसा दिखता है, इसलिए इसका नाम Buckminsterfullerene रखा गया [NCERT p.60]।

Checkpoint Question Checkpoint Question

Why does graphite conduct electricity whereas diamond does not? [NCERT p.59] Graphite electricity conduct करता है जबकि diamond नहीं, ऐसा क्यों? [NCERT p.59]

Section Summary (सहसंयोजी आबंध का सारांश)

Carbon forms covalent bonds by sharing its four valence electrons, as gaining or losing four electrons is energetically difficult [NCERT pp. 58-59].
Covalent compounds have strong bonds within molecules but weak intermolecular forces, resulting in low melting/boiling points and non-conductivity [NCERT p. 59].
Allotropes of carbon have different physical structures: Diamond is a rigid 3D lattice, Graphite has slippery conductive layers, and Buckminsterfullerene is a C-60 spherical cage [NCERT p. 60].

2. Versatile Nature of Carbon कार्बन की सर्वतोमुखी प्रकृति

Goal: Explore how carbon forms millions of compounds through catenation and tetravalency. Learn to write structures, isomers, and IUPAC names.

The number of carbon compounds whose formulas are known to chemists was recently estimated to be in millions. This outnumbers the compounds formed by all other elements put together. This unique ability is due to two key properties [NCERT p.62]: Chemists द्वारा जाने जाने वाले carbon compounds की संख्या हाल ही में millions में estimate की गई है। यह दूसरे सभी elements द्वारा बनाए गए compounds को मिलाकर भी उनसे बहुत ज्यादा है। यह unique ability दो key properties की वजह से है [NCERT p.62]:

Catenation: Carbon has the unique ability to form covalent bonds with other carbon atoms, giving rise to long chains, branched chains, or closed rings. Carbon-carbon bonds are exceptionally strong and stable [NCERT p.62]. Catenation: Carbon के पास दूसरे carbon atoms के साथ covalent bonds बनाने की एक unique ability होती है, जिससे long chains, branched chains, या closed rings बनती हैं। Carbon-carbon bonds बहुत strong और stable होते हैं [NCERT p.62]।
Tetravalency: Since carbon has a valency of 4, it is capable of bonding with four other carbon atoms or atoms of other monovalent elements like Hydrogen, Chlorine, Oxygen, Nitrogen, and Sulphur [NCERT p.62]. Tetravalency: चूंकि carbon की valency 4 होती है, इसलिए यह 4 दूसरे carbon atoms या Hydrogen, Chlorine, Oxygen, Nitrogen, और Sulphur जैसे monovalent elements के atoms के साथ bond बना सकता है [NCERT p.62]।

Classification of Hydrocarbons (हाइड्रोकार्बन का वर्गीकरण)

Hydrocarbons
(हाइड्रोकार्बन)

→

Saturated
Alkanes (C-C single bond)

•

Unsaturated
Alkenes (C=C) & Alkynes (C≡C)

Saturated and Unsaturated Hydrocarbons Saturated और Unsaturated Hydrocarbons

Saturated Hydrocarbons (संतृप्त हाइड्रोकार्बन): Compounds of carbon and hydrogen containing only single bonds between the carbon atoms. They are called alkanes (general formula: C_nH_2n+2) [NCERT p.64]. They are generally unreactive. Saturated Hydrocarbons: Carbon और hydrogen के ऐसे compounds जिनमें carbon atoms के बीच सिर्फ single bonds होते हैं। इन्हें alkanes कहते हैं (general formula: C_nH_2n+2) [NCERT p.64]। ये आमतौर पर unreactive (अक्रिय) होते हैं।
Unsaturated Hydrocarbons (असंतृप्त हाइड्रोकार्बन): Carbon-hydrogen compounds containing one or more double bonds (alkenes, C_nH_2n) or triple bonds (alkynes, C_nH_2n−2) between carbon atoms [NCERT p.64]. They are highly reactive. Unsaturated Hydrocarbons: ऐसे compounds जिनमें carbon atoms के बीच एक या एक से ज्यादा double bonds (alkenes, C_nH_2n) या triple bonds (alkynes, C_nH_2n−2) होते हैं [NCERT p.64]। ये बहुत reactive होते हैं।

Homologous Series (समजातीय श्रेणी)

A group of organic compounds having the same functional group and similar chemical properties, where successive members differ by a −CH₂− unit (or a molecular mass of 14 u) [NCERT p.66]. Try out the builder below to see the trend: Organic compounds का ऐसा group जिसमें same functional group और similar chemical properties होती हैं, और successive members के बीच −CH₂− unit (या 14 u molecular mass) का अंतर होता है, उसे homologous series कहते हैं [NCERT p.66]। इस trend को समझने के लिए नीचे दिए गए builder को try करें:

Chain Metrics

Formula: CH₄

IUPAC Name:IUPAC Name: Methane

Molar Mass:Molar Mass (मोलर mass): 16 u

Boiling Point:Boiling Point (क्वथनांक): -161.5 °C

2D Chemical Structure 2D Chemical Structure (2D structure)

Isomerism (समावयवता)

Organic compounds having the same molecular formula but different structural arrangements are called structural isomers, and this property is called structural isomerism [NCERT p.65]. For example, butane (C₄H₁₀) has two structural isomers: ऐसे organic compounds जिनका same molecular formula होता है लेकिन different structural arrangements होते हैं, उन्हें structural isomers (समावयव) कहते हैं, और इस property को structural isomerism कहते हैं [NCERT p.65]। Example के लिए, butane (C₄H₁₀) के दो structural isomers होते हैं:

n-Butane (straight chain): CH₃−CH₂−CH₂−CH₃ n-Butane (straight chain): CH₃−CH₂−CH₂−CH₃
Isobutane / 2-Methylpropane (branched chain): CH₃−CH(CH₃)−CH₃ Isobutane / 2-Methylpropane (branched chain): CH₃−CH(CH₃)−CH₃

Nomenclature of Carbon Compounds

Compounds are named by identifying the carbon chain length, followed by a suffix/prefix corresponding to the functional group present [NCERT p.67]. Explore the functional groups in the table below: Compounds का नामकरण carbon chain की length पहचानकर और उसके functional group के suffix/prefix के rules के अनुसार किया जाता है [NCERT p.67]। नीचे दी गई table में functional groups को explore करें:

Class of Compounds	Functional Group	Prefix / Suffix	Example	IUPAC Name
Halogens	−Cl, −Br, −I	Prefix: chloro-, bromo-	CH₃−CH₂−Cl	Chloromethane / Chloroethane
Alcohol	−OH	Suffix: -ol	CH₃−CH₂−OH	Ethanol
Aldehyde	−CHO	Suffix: -al	CH₃−CHO	Ethanal
Ketone	>C=O	Suffix: -one	CH₃−CO−CH₃	Propanone
Carboxylic Acid	−COOH	Suffix: -oic acid	CH₃−COOH	Ethanoic acid
Alkene	>C=C<	Suffix: -ene	CH₂=CH₂	Ethene
Alkyne	−C≡C−	Suffix: -yne	CH≡CH	Ethyne

Interactive 3D Molecule Presenter

Use the Three.js 3D WebGL viewer below to rotate, zoom, and analyze the shapes and bond angles of carbon compounds. If Three.js fails, a high-quality SVG will load automatically: नीचे दिए गए Three.js 3D WebGL viewer का use करके carbon compounds की shapes और bond angles को rotate, zoom और analyze करें। अगर Three.js load न हो, तो high-quality SVG automatic load हो जाएगा:

3D Ball-and-Stick Viewer

Three.js Active

Methane (CH₄): A tetrahedral arrangement of 4 Hydrogen atoms surrounding a central Carbon atom. The H-C-H bond angle is approximately 109.5°, showing optimal spacing to minimize electron-pair repulsion.

Checkpoint Question Checkpoint Question

How many structural isomers are possible for Pentane (C₅H₁₂)? [NCERT p.65] Pentane (C₅H₁₂) के लिए कितने structural isomers possible हैं? [NCERT p.65]

Section Summary (कार्बन की सर्वतोमुखी प्रकृति का सारांश)

Carbon forms millions of compounds due to catenation (self-linking to form chains/rings) and its tetravalency (bonding with 4 other atoms) [NCERT pp. 61-62].
Saturated hydrocarbons contain only single C-C bonds (alkanes), while unsaturated ones contain double or triple bonds (alkenes and alkynes) and are more reactive [NCERT pp. 62-63].
Functional groups replace hydrogen in carbon chains and determine their chemical behavior; a homologous series is a family differing by -CH₂- units [NCERT pp. 65-66].

3. Chemical Properties of Carbon Compounds कार्बन यौगिकों के रासायनिक गुणधर्म

Goal: Learn the four primary chemical reactions of carbon compounds: combustion, oxidation, addition, and substitution, with interactive step-by-step animations.

Carbon compounds exhibit characteristic chemical behaviors. Let us study the four fundamental reaction types [NCERT p.69-71]: Carbon compounds specific chemical behaviors show करते हैं। आइए, 4 fundamental reaction types का study करें [NCERT p.69-71]:

Combustion: Carbon burns in oxygen to release carbon dioxide, water vapor, heat, and light [NCERT p.69].
CH₄ + 2O₂ → CO₂ + 2H₂O + Heat & Light
Saturated hydrocarbons yield clean, blue flames. Unsaturated hydrocarbons burn with yellow, smoky flames due to incomplete combustion of carbon particles. Combustion: Carbon oxygen की presence में burn होकर carbon dioxide, water vapor, heat, और light release करता है [NCERT p.69]।
CH₄ + 2O₂ → CO₂ + 2H₂O + Heat & Light
Saturated hydrocarbons clean, blue flame के साथ जलते हैं। Unsaturated hydrocarbons incomplete combustion के कारण yellow, smoky flame देते हैं।
Oxidation: Carbon compounds like alcohols can be oxidized to carboxylic acids using oxidizing agents like alkaline Potassium Permanganate (KMnO₄) or acidified Potassium Dichromate (K₂Cr₂O₇) [NCERT p.70].
CH₃CH₂OH + 2[O] → CH₃COOH + H₂O Oxidation: Alcohols जैसे carbon compounds को alkaline KMnO₄ या acidified K₂Cr₂O₇ जैसे oxidizing agents की help से carboxylic acids में oxidize किया जा सकता है [NCERT p.70]।
CH₃CH₂OH + 2[O] → CH₃COOH + H₂O
Addition Reaction (संकलन अभिक्रिया): Unsaturated hydrocarbons add hydrogen in the presence of catalysts like Nickel (Ni) or Palladium (Pd) to form saturated hydrocarbons [NCERT p.70]. This is used in the hydrogenation of vegetable oils.
R₂C=CR₂ + H₂ → R₂CH−CHR₂ (Catalyst: Ni) Addition Reaction (संकलन reaction): Unsaturated hydrocarbons catalyst (जैसे Nickel या Palladium) की presence में hydrogen add करके saturated hydrocarbons बनाते हैं [NCERT p.70]। इसका use vegetable oils के hydrogenation में किया जाता है।
R₂C=CR₂ + H₂ → R₂CH−CHR₂ (Catalyst: Ni)
Substitution Reaction (प्रतिस्थापन अभिक्रिया): In the presence of sunlight, chlorine atoms sequentially replace hydrogen atoms in saturated hydrocarbons [NCERT p.71].
CH₄ + Cl₂ → CH₃Cl + HCl (in Sunlight) Substitution Reaction (प्रतिस्थापन reaction): Sunlight की presence में chlorine atoms saturated hydrocarbons के hydrogen atoms को एक-एक करके replace करते हैं [NCERT p.71]।
CH₄ + Cl₂ → CH₃Cl + HCl (in Sunlight)

Reaction Mechanism Animators

Select a tab below to play animations showing exactly how chemical bonds cleave and rearrange to form products, including by-products: नीचे दिए गए tabs में से किसी को select करके animation play करें और देखें कि products (और by-products) बनने के लिए chemical bonds कैसे टूटते और rearrange होते हैं:

CH₄ + Cl₂ → CH₃Cl + HCl

Click "Play Mechanism" to watch a chlorine atom displace a hydrogen atom from methane under sunlight, producing hydrogen chloride (HCl) as a by-product.

Checkpoint Question Checkpoint Question

Why is the addition reaction (hydrogenation) of vegetable oils industrially important? [NCERT p.70] Vegetable oils का addition reaction (hydrogenation) industrially important क्यों है? [NCERT p.70]

Section Summary (रासायनिक गुणधर्मों का सारांश)

Combustion of carbon compounds releases carbon dioxide, water, heat, and light. Saturated hydrocarbons burn clean, while unsaturated ones burn with a sooty flame [NCERT pp. 69-70].
Alcohols undergo oxidation to form carboxylic acids using alkaline KMnO₄ or acidified K₂Cr₂O₇ [NCERT p. 70].
Addition reactions hydrogenate unsaturated hydrocarbons (nickel catalyst), while substitution reactions replace hydrogen in saturated hydrocarbons with chlorine in sunlight [NCERT pp. 70-71].

4. Important Carbon Compounds — Ethanol & Ethanoic Acid महत्वपूर्ण कार्बनिक यौगिक: एथेनॉल और एथेनॉइक अम्ल

Goal: Learn the properties, reactions, and differences between Ethanol (alcohols) and Ethanoic Acid (carboxylic acids). Visualize esterification.

Two commercially vital carbon compounds are studied in detail [NCERT p.71-74]: दो commercially important carbon compounds को यहाँ detail में समझाया गया है [NCERT p.71-74]:

1. Ethanol (एथेनॉल / C₂H₅OH)

Physical Properties: Liquid at room temperature, melting point 156 K, boiling point 351 K. Soluble in water in all proportions. It is active ingredient of alcoholic beverages [NCERT p.71]. Physical Properties: Room temperature पर liquid, melting point 156 K, boiling point 351 K होता है। यह water में सभी proportions में soluble है। यह alcoholic beverages का active ingredient है [NCERT p.71]।
Reaction with Sodium: Releases hydrogen gas with sodium metal [NCERT p.72].
2Na + 2CH₃CH₂OH → 2CH₃CH₂ONa + H₂ (Sodium Ethoxide) Reaction with Sodium: Sodium metal के साथ react करके hydrogen gas release करता है [NCERT p.72]।
2Na + 2CH₃CH₂OH → 2CH₃CH₂ONa + H₂ (Sodium Ethoxide)
Dehydration: Heating ethanol at 443 K with excess concentrated sulphuric acid dehydrates it into ethene [NCERT p.72].
CH₃CH₂OH → CH₂=CH₂ + H₂O (Catalyst: hot conc. H₂SO₄) Dehydration: Ethanol को 443 K पर excess conc. H₂SO₄ के साथ गर्म करने पर यह dehydrate होकर ethene बनाता है [NCERT p.72]।
CH₃CH₂OH → CH₂=CH₂ + H₂O (Catalyst: hot conc. H₂SO₄)

2CH₃CH₂OH + 2Na → 2CH₃CH₂ONa + H₂

Click "Play Mechanism" to watch Sodium replace the acidic hydrogen in Ethanol, releasing Hydrogen gas (H₂) and forming Sodium Ethoxide.

2. Ethanoic Acid (एथेनॉइक अम्ल / CH₃COOH)

Physical Properties: Also called acetic acid. 5-8% solution in water is vinegar. Pure ethanoic acid melts at 290 K, often freezing in winter, giving it the name glacial acetic acid [NCERT p.73]. Physical Properties: इसे acetic acid भी कहते हैं। इसका water में 5-8% solution vinegar (सिरका) कहलाता है। Pure ethanoic acid 290 K पर melt होता है, और ठंड में जम जाता है, इसलिए इसे glacial acetic acid भी कहते हैं [NCERT p.73]।
Esterification Reaction (एस्टरीकरण): Ethanoic acid reacts with absolute ethanol in the presence of an acid catalyst to form sweet-smelling esters [NCERT p.73].
CH₃COOH + CH₃CH₂OH → CH₃COOCH₂CH₃ + H₂O (Ethyl Ethanoate) Esterification Reaction (एस्टरीकरण): Ethanoic acid catalyst (acid) की presence में absolute ethanol के साथ react करके sweet-smelling esters बनाता है [NCERT p.73]।
CH₃COOH + CH₃CH₂OH → CH₃COOCH₂CH₃ + H₂O (Ethyl Ethanoate)
Saponification (साबुनीकरण): Esters react with alkalies (NaOH) to regenerate alcohol and the sodium salt of carboxylic acid (soap) [NCERT p.74].
CH₃COOCH₂CH₃ + NaOH → CH₃COONa + CH₃CH₂OH Saponification (साबुनीकरण): Esters alkalies (NaOH) के साथ react करके वापस alcohol और carboxylic acid का sodium salt (soap) बनाते हैं [NCERT p.74]।
CH₃COOCH₂CH₃ + NaOH → CH₃COONa + CH₃CH₂OH
Reaction with Carbonates & Hydrogencarbonates: Releases carbon dioxide gas with effervescence [NCERT p.74].
2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂ Reaction with Carbonates & Hydrogencarbonates: Carbonates और hydrogencarbonates के साथ react करके brisk effervescence के साथ carbon dioxide release करता है [NCERT p.74]।
2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂

Organic Compounds & Reactions Animators

Esterification splits off water molecules ($H_2O$) as by-products. Saponification hydrolyzes it back. Play the mechanism below: Esterification में water molecules ($H_2O$) by-product के रूप में निकलते हैं। Saponification इसे hydrolyze करके वापस separate करता है। नीचे mechanism play करें:

CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O

Click "Play Mechanism" to watch absolute Ethanol react with Ethanoic Acid. The OH group splits from ethanoic acid and the H atom splits from ethanol to form a separate water (H₂O) by-product.

Checkpoint Question Checkpoint Question

What occurs when sodium hydrogen carbonate (NaHCO₃) is added to ethanoic acid? [NCERT p.74] जब sodium hydrogen carbonate (NaHCO₃) को ethanoic acid में add किया जाता है तो क्या होता है? [NCERT p.74]

Section Summary (एथेनॉल और एथेनॉइक अम्ल का सारांश)

Ethanol (C₂H₅OH) is a liquid that reacts with sodium to release hydrogen gas, and is dehydrated to ethene using hot concentrated sulphuric acid [NCERT pp. 72-73].
Ethanoic acid (CH₃COOH) is a weak acid that reacts with ethanol (esterification) to produce sweet-smelling esters, which can be hydrolysed back to soap (saponification) [NCERT pp. 73-74].
Esters are sweet-smelling compounds used in perfumes and flavoring agents [NCERT p. 74].

5. Soaps and Detergents साबुन और अपमार्जक

Goal: Master the structure of soap molecules, micelle formation, and why soaps fail in hard water while detergents succeed.

Soaps are sodium or potassium salts of long-chain carboxylic acids (fatty acids) [NCERT p.75]. A soap molecule has two parts: Soaps long-chain carboxylic acids (fatty acids) के sodium या potassium salts होते हैं [NCERT p.75]। Soap molecule के दो parts होते हैं:

Hydrophilic Ionic Head (जलरागी सिर): The carboxylate head (−COO⁻Na⁺) which is polar and interacts with water [NCERT p.75]. Hydrophilic Ionic Head: Carboxylate head (−COO⁻Na⁺) जो polar होता है और water के साथ interact करता है [NCERT p.75]।
Hydrophobic Hydrocarbon Tail (जलविरागी पूंछ): The long hydrocarbon chain which is non-polar, repels water, and dissolves in oils/dirt/grease [NCERT p.75]. Hydrophobic Hydrocarbon Tail: लंबी hydrocarbon chain जो non-polar होती है, water को repel करती है और oils/dirt/grease में dissolve हो जाती है [NCERT p.75]।

Cleansing Action and Micelle Formation Cleansing Action और Micelle Formation

When soap is dissolved in water, the molecules arrange themselves in a spherical shape called a micelle [NCERT p.75]. The hydrophobic tails point inward, trapping the dirt/grease at the center, while the hydrophilic ionic heads point outward, facing the water. This forms an emulsion that is washed away by running water. जब soap को water में dissolve किया जाता है, तो molecules खुद को एक spherical shape में arrange कर लेते हैं जिसे micelle कहते हैं [NCERT p.75]। इसमें hydrophobic tails अंदर की तरफ point करती हैं, जो center में dirt/grease को trap कर लेती हैं, जबकि hydrophilic ionic heads बाहर की तरफ point करते हैं और water को face करते हैं। इससे एक emulsion बनता है जो बहते पानी के साथ साफ हो जाता है।

Micelle Assembly Lab

Watch how soap molecules orient themselves radially with hydrophobic tails embedding in grease and hydrophilic heads sticking out in water. देखें कि soap molecules कैसे radially खुद को orient करते हैं, जहाँ hydrophobic tails grease में embed हो जाती हैं और hydrophilic heads water में बाहर की तरफ रहते हैं।

Hard Water and Scum Formation Hard Water और Scum Formation

Hard water contains Calcium (Ca²⁺) and Magnesium (Mg²⁺) salts [NCERT p.76]. When soap is added to hard water, it reacts with these ions to form an insoluble precipitate called scum [NCERT p.76]. This wastes soap and reduces its cleansing effect. Hard water में Calcium (Ca²⁺) और Magnesium (Mg²⁺) salts होते हैं [NCERT p.76]। जब soap को hard water में add किया जाता है, तो यह इन ions के साथ react करके एक insoluble precipitate बनाता है जिसे scum कहते हैं [NCERT p.76]। इससे soap waste होता है और उसकी cleansing effect कम हो जाती है।

Detergents (अपमार्जक): Detergents are ammonium or sulphonate salts of long-chain carboxylic acids. They do not form insoluble precipitates (scum) with Calcium and Magnesium ions in hard water, and therefore remain effective cleansers even in hard water [NCERT p.76].

Checkpoint Question Checkpoint Question

Why is soap ineffective in hard water? [NCERT p.76] Soap hard water में ineffective क्यों होता है? [NCERT p.76]

Section Summary (साबुन और अपमार्जक का सारांश)

Soaps are sodium/potassium salts of long-chain fatty acids with a hydrophilic ionic head and a hydrophobic hydrocarbon tail [NCERT p. 74].
Soaps clean by forming micelles, trapping grease in the center and allowing it to be washed away in water [NCERT p. 75].
Soaps fail in hard water by forming scum with calcium/magnesium. Detergents (sulphonic acid salts) work in hard water without forming scum [NCERT p. 76].

NCERT Solutions पाठ्यपुस्तक के प्रश्न-उत्तर

Q1. What would be the electron dot structure of carbon dioxide which has the formula CO₂? [NCERT p.61] Q1. Carbon dioxide (CO₂) का electron dot structure क्या होगा? [NCERT p.61]

Answer: Carbon (atomic number 6) has 4 valence electrons (2,4). Oxygen (atomic number 8) has 6 valence electrons (2,6). To achieve octet configuration, the carbon atom shares two pairs of electrons with each of the two oxygen atoms, forming two double covalent bonds: Answer: Carbon (atomic number 6) के पास 4 valence electrons (2,4) होते हैं। Oxygen (atomic number 8) के पास 6 valence electrons (2,6) होते हैं। Octet configuration पाने के लिए, carbon atom दोनों oxygen atoms के साथ दो-दो pairs of electrons share करता है, जिससे दो double covalent bonds बनते हैं:

This sharing results in CO₂ represented as O=C=O. इस sharing के कारण CO₂ को O=C=O के रूप में represent किया जाता है।

Q2. What would be the electron dot structure of a molecule of sulphur which is made up of eight atoms of sulphur? [NCERT p.61] Q2. Sulphur के molecule का electron dot structure क्या होगा जो sulphur के आठ atoms से बना होता है? [NCERT p.61]

Answer: Sulphur (atomic number 16) has 6 valence electrons (2,8,6). Eight sulphur atoms share one electron pair with each of their two neighboring sulphur atoms, forming a closed ring (resembling a crown): Answer: Sulphur (atomic number 16) के पास 6 valence electrons (2,8,6) होते हैं। आठ sulphur atoms अपने दो neighboring sulphur atoms के साथ एक-एक electron pair share करते हैं, जिससे एक closed ring बनती है (जो एक crown जैसी दिखती है):

The crown/ring structure joins 8 sulphur atoms sequentially via single covalent bonds: S−S−S−S−S−S−S−S, forming a puckered octagon loop. Crown/ring structure 8 sulphur atoms को single covalent bonds: S−S−S−S−S−S−S−S के जरिए जोड़कर एक puckered octagon loop बनाती है।

Q3. What are the two properties of carbon which lead to the huge number of carbon compounds we see around us? [NCERT p.68] Q3. Carbon की वो दो properties कौन सी हैं जिनकी वजह से हमारे चारों ओर carbon compounds की इतनी बड़ी संख्या दिखाई देती है? [NCERT p.68]

Catenation: Carbon atoms can bond together in straight chains, branched chains, or rings via strong covalent bonds. Catenation: Carbon atoms strong covalent bonds के जरिए straight chains, branched chains, या rings में आपस में जुड़ सकते हैं।
Tetravalency: Carbon can form bonds with up to four other monovalent or divalent atoms (H, Cl, O, N, S). Tetravalency: Carbon चार दूसरे monovalent या divalent atoms (H, Cl, O, N, S) के साथ bonds बना सकता है।

Q4. Explain the nature of the covalent bond using the bond formation in CH₃Cl. [NCERT p.77] Q4. CH₃Cl में bond formation का use करके covalent bond के nature को समझाएं। [NCERT p.77]

Answer: Chloromethane (CH₃Cl) consists of a central carbon atom bonded to three Hydrogen atoms and one Chlorine atom. Carbon shares 3 of its valence electrons with 3 hydrogen atoms (single bonds) and its 4th valence electron with 1 chlorine atom (single bond). Since sharing occurs, these are covalent bonds. They have strong forces within the molecule, but weak intermolecular forces, giving CH₃Cl a low melting/boiling point. The C−Cl bond is slightly polar due to chlorine's higher electronegativity. Answer: Chloromethane (CH₃Cl) में एक central carbon atom होता है जो तीन Hydrogen atoms और एक Chlorine atom से जुड़ा होता है। Carbon अपने 3 valence electrons को 3 hydrogen atoms के साथ (single bonds) और अपने चौथे valence electron को 1 chlorine atom के साथ (single bond) share करता है। चूंकि यहाँ sharing होती है, इसलिए ये covalent bonds हैं। इनमें intra-molecular forces (अणुओं के भीतर का बल) strong होते हैं, लेकिन inter-molecular forces (अंतर-आणविक बल) weak होते हैं, जिससे CH₃Cl का melting/boiling point बहुत low होता है। Chlorine की high electronegativity की वजह से C−Cl bond थोड़ा polar (ध्रुवीय) होता है।

Q5. Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents like ethanol? [NCERT p.77] Q5. जब soap को water में add किया जाता है तो micelle formation क्यों होता है? क्या ethanol जैसे solvents में भी micelle बनेगा? [NCERT p.77]

Answer: Micelle formation occurs because soap molecules have a hydrophobic tail (insoluble in water) and a hydrophilic head (soluble in water). In water, the tails cluster together inside to hide from water, while the ionic heads point outwards to interact with water, forming a micelle. Answer: Soap molecules में एक hydrophobic tail (जो water में insoluble है) और एक hydrophilic head (जो water में soluble है) होता है। Water में, tails पानी से बचने के लिए अंदर की तरफ cluster (गुच्छा) बना लेती हैं, जबकि ionic heads बाहर की तरफ रहकर water से interact करते हैं, जिससे micelle बनता है।

In other solvents like ethanol, micelle formation will not take place. This is because the non-polar hydrocarbon tails of soap are soluble in ethanol (a less polar organic solvent), so they do not need to hide inside a cluster; they remain dissolved individually. Ethanol जैसे solvents में micelle formation नहीं होगा। ऐसा इसलिए है क्योंकि soap की non-polar hydrocarbon tails organic solvent ethanol में easily soluble होती हैं, इसलिए वे cluster के अंदर छिपने के बजाय individual रूप से dissolved रहती हैं।

Solved Previous Years' Questions (PYQs) बोर्ड परीक्षा के हल प्रश्न

1-Mark Questions (Very Short Answer)

Q1. Write the molecular formula of the second member of the homologous series of alkenes. [CBSE 2019, 2022] Q1. Alkenes की homologous series के दूसरे member का molecular formula लिखें। [CBSE 2019, 2022]

Ans: The general formula for alkenes is C_nH_2n. The first member is Ethene (C₂H₄, n=2). Therefore, the second member of the series is Propene, with the molecular formula C₃H₆ [NCERT p.66]. Ans: Alkenes का general formula C_nH_2n होता है। इसका पहला member Ethene (C₂H₄, n=2) है। इसलिए, इस series का दूसरा member Propene होगा, जिसका molecular formula C₃H₆ है [NCERT p.66]।

3-Mark Questions (Short Answer Type II)

Q2. Write chemical equations for the following reactions of ethanoic acid: (a) Esterification, (b) Saponification, (c) Reaction with sodium hydrogen carbonate. [CBSE 2018, 2020] Q2. Ethanoic acid की इन reactions के chemical equations लिखें: (a) Esterification, (b) Saponification, (c) Reaction with sodium hydrogen carbonate. [CBSE 2018, 2020]

Ans: The chemical equations are: Ans: इन reactions के chemical equations इस प्रकार हैं:

(a) Esterification: Ethanoic acid reacts with absolute ethanol in presence of an acid catalyst to produce ethyl ethanoate [NCERT p.73]: (a) Esterification: Ethanoic acid, acid catalyst की presence में absolute ethanol के साथ react करके ethyl ethanoate बनाता है [NCERT p.73]:
CH₃COOH + CH₃CH₂OH → CH₃COOCH₂CH₃ + H₂O
(b) Saponification: Hydrolysis of ethyl ethanoate in presence of sodium hydroxide [NCERT p.74]: (b) Saponification: Sodium hydroxide की presence में ethyl ethanoate का hydrolysis:
CH₃COOCH₂CH₃ + NaOH → CH₃COONa + CH₃CH₂OH
(c) Reaction with NaHCO₃: Ethanoic acid reacts with sodium hydrogen carbonate to release carbon dioxide [NCERT p.74]: (c) Reaction with NaHCO₃: Ethanoic acid, sodium hydrogen carbonate के साथ react करके carbon dioxide release करता है [NCERT p.74]:
CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂

5-Mark Questions (Long Answer)

Q3. A compound 'X' is a key constituent of wine and beer. On heating 'X' with excess concentrated H₂SO₄ at 443 K, it gives compound 'Y'. Compound 'X' on oxidation with alkaline KMnO₄ gives compound 'Z'. Identify X, Y, and Z. Write the chemical equations involved. [CBSE 2017, 2021] Q3. एक compound 'X' wine और beer का key constituent है। 'X' को 443 K पर excess concentrated H₂SO₄ के साथ गर्म करने पर compound 'Y' बनता है। 'X' को alkaline KMnO₄ के साथ oxidize करने पर compound 'Z' बनता है। X, Y, और Z को identify करें और involved chemical equations लिखें। [CBSE 2017, 2021]

Ans: Let us identify the compounds sequentially: Ans: आइए compounds को sequentially identify करें:

Identification:Identification:
- Compound X: Since it is the key constituent of wine and beer, X is Ethanol (C₂H₅OH) [NCERT p.71]. Compound X: चूंकि यह wine और beer का key constituent है, इसलिए X Ethanol (C₂H₅OH) है [NCERT p.71]।
- Compound Y: Heating ethanol with conc. H₂SO₄ at 443 K dehydrates it to form Ethene (C₂H₄) [NCERT p.72]. Compound Y: Ethanol को 443 K पर conc. H₂SO₄ के साथ गर्म करने पर यह dehydrate होकर Ethene (C₂H₄) बनाता है [NCERT p.72]।
- Compound Z: Oxidation of ethanol with alkaline KMnO₄ yields Ethanoic Acid (CH₃COOH) [NCERT p.70]. Compound Z: Ethanol को alkaline KMnO₄ के साथ oxidize करने पर Ethanoic Acid (CH₃COOH) बनता है [NCERT p.70]।
Chemical Equations:Chemical Equations:
- Reaction 1 (Dehydration of Ethanol to Ethene): Reaction 1 (Dehydration of Ethanol to Ethene):
  CH₃CH₂OH → CH₂=CH₂ + H₂O (at 443 K, excess conc. H₂SO₄)
- Reaction 2 (Oxidation of Ethanol to Ethanoic Acid): Reaction 2 (Oxidation of Ethanol to Ethanoic Acid):
  CH₃CH₂OH + 2[O] → CH₃COOH + H₂O (Alkaline KMnO₄ + Heat)