Model Test Questions XII Chemistry Chapter 7 (Alcohols & Ethers) | Board-Focused Practice by Inam Jazbi

Class 12 Chemistry – Alcohols & Ethers

🧪 Class 12 Chemistry – Chapter 7: Alcohols & Ethers ✨

Preparing for Class 12 Chemistry exams and worried about Chapter 7: Alcohols and Ethers? 😟 You’re in the right place! ✅

In this blog, Inam Jazbi’s smart, board-oriented model test questions are carefully designed to sharpen your concepts, boost your confidence 💪, and help you score maximum marks 📈.

These questions strictly follow the latest exam pattern, covering important numericals, MCQs, short and long questions, with special focus on the areas examiners love to repeat 🔁.

If you want easy understanding + high scores 🏆, this guide is a must-read before your chemistry paper! 📘🔥

Short Answer Questions

✏️ Model Test Questions XII Chemistry Chapter # 7………… Alcohols and Ethers ✏️

Short Answer Questions

✏️ Short Questions of Alcohols and Ethers ✏️

Alcohols and Ethers – Short Questions
Q1. What are alcohols? How are alcohols classified? Define primary, secondary and tertiary alcohols. Write the structures and names of primary, secondary and tertiary alcohols of the molecular formula C₅H₁₁OH (8 isomers).
Q2. Give two examples of each of monohydric, dihydric and trihydric alcohols with their IUPAC names.
Q3. Write the equations for the following chemical processes:
(i) Reduction of acetic acid with LiAlH₄
(ii) Hydration of ethene with hot concentrated H₂SO₄
(iii) Oxidation of ethanol with acidified dichromate
(iv) Hydrolysis of diazonium salt
(v) Condensation of alcohols into ether
Q4. Explain the following scientific reasons:
(i) Boiling point of ether is less than alcohol
(ii) Alcohols are soluble in water
(iii) Ethanol is liquid but ethyl chloride is gas at room temperature
Q5. Identify alcohol with two laboratory tests.
Q6. What is Lucas reagent? Describe its use to distinguish between primary, secondary and tertiary alcohols.
Q7. What is oxonium ion? How can ether form oxonium ion?
Short Answer Questions

✏️ Descriptive Questions of Alcohols and Ethers ✏️

Alcohols & Phenols – Questions
Q1. Starting from Grignard reagent how is primary, secondary and tertiary alcohol prepared?
Q2. Write the equations for the following possible conversions:
(i) Ethyl alcohol to diethyl ether
(ii) Phenol into benzoquinone
(iii) Ethyl bromide to ethanol
(iv) 2°-alcohol to carboxylic acid
(v) Ethanol into acetic acid
(vi) Ethyl alcohol into ethyne
(vii) Ethene into ethanol
Q3. Differentiate between alcohol and phenol on the basis of:
(i) Solubility in water
(ii) Boiling point
(iii) Acidic character
Q4. Write the equation and name of the final product when phenol reacts with the following:
(i) Hot and concentrated nitric acid
(ii) Concentrated sulphuric acid at 100°C
(iii) Bromine water
(iv) Sodium metal
Q5. Enlist the commercial applications of alcohol, phenol and ether.
Q6. How do you prepare alcohol from carbonyl compounds, alkenes and esters?
Short Answer Questions

✏️ Text Book Multiple Choice Questions on Chapter 7 ✏️

MCQs – Alcohols & Phenols
1. In the molecule of phenol, the carbon atom which is attached to hydroxyl group is
(a) sp-hybridized
(b) sp²-hybridized
(c) sp³-hybridized
(d) Unhybridized
✔ Correct Answer: (b) sp²-hybridized
Reason: The carbon is part of an aromatic ring, therefore it is sp²-hybridized.
2. Which of the following is a trihydric phenol?
(a) Resorcinol
(b) Cresol
(c) Pyrogallol
(d) Catechol
✔ Correct Answer: (c) Pyrogallol
Reason: Pyrogallol contains three –OH groups, hence it is trihydric.
3. Ethanol reacts with PCl₃ to form
(a) Diethyl ether
(b) Ethene
(c) Ethyl chloride
(d) Ethanoic acid
✔ Correct Answer: (c) Ethyl chloride
Reason: PCl₃ replaces the –OH group of alcohol with –Cl.
4. Which of the following alcohols has the highest boiling point?
(a) Neo-pentyl alcohol
(b) n-pentyl alcohol
(c) Iso-pentyl alcohol
(d) Ethyl alcohol
✔ Correct Answer: (b) n-pentyl alcohol
Reason: Straight-chain alcohols have stronger intermolecular forces.
5. Which product is mainly formed when ethanol is dehydrated with conc. H₂SO₄ at 170°C?
(a) Ethene
(b) Ethyne
(c) Ethanol
(d) Diethyl ether
✔ Correct Answer: (a) Ethene
Reason: At 170°C, dehydration of ethanol leads to elimination forming ethene.
6. Lucas reagent is a mixture of
(a) Zn and Hg
(b) NaOH and CaO
(c) ZnCl₂ and HCl
(d) Zn and HCl
✔ Correct Answer: (c) ZnCl₂ and HCl
Reason: Lucas reagent consists of anhydrous ZnCl₂ dissolved in concentrated HCl.
7. Oxidative cleavage of 1,2-diol occurs in the presence of
(a) K₂Cr₂O₇
(b) KMnO₄
(c) HNO₃
(d) HIO₄
✔ Correct Answer: (d) HIO₄
Reason: Periodic acid (HIO₄) cleaves vicinal diols by oxidative cleavage.
8. Which of the following molecule cannot form hydrogen bonding with water molecule?
(a) Phenol
(b) Resorcinol
(c) Ethyl chloride
(d) Ethyl alcohol
✔ Correct Answer: (c) Ethyl chloride
Reason: Ethyl chloride does not contain –OH or –NH group required for hydrogen bonding.
9. Secondary alcohols undergo oxidation with potassium dichromate to produce carboxylic acid through an intermediate product known as
(a) Aldehyde
(b) Ketone
(c) Ether
(d) Alkyl halide
✔ Correct Answer: (b) Ketone
Reason: Secondary alcohols are first oxidized to ketones during oxidation.
10. Which of the following is an anaesthetic agent?
(a) Phenol
(b) Ethyl alcohol
(c) Diethyl ether
(d) Acetone
✔ Correct Answer: (c) Diethyl ether
Reason: Diethyl ether has been used as a general anaesthetic.
Short Answer Questions

✏️ Multiple Choice Questions on Alcohols and Ethers from Past Papers✏️

1. Which of the following is a dihydric alcohol?
(a) Ethanol
(b) Isobutyl alcohol
(c) Ethylene glycol
(d) Glycerol
✔ Correct Answer: (c) Ethylene glycol
Reason: Ethylene glycol (HO–CH₂–CH₂–OH) has two hydroxyl groups, making it dihydric.
2. Which of the following is a trihydric alcohol?
(a) Ethanol
(b) Isobutyl alcohol
(c) Ethylene glycol
(d) Glycerol
✔ Correct Answer: (d) Glycerol
Reason: Glycerol (HO–CH₂–CHOH–CH₂–OH) has three –OH groups, hence trihydric.
3. Which type of isomerism is shown by alcohols?
(a) Chain isomerism
(b) Position isomerism
(c) Functional isomerism
(d) All of them
✔ Correct Answer: (d) All of them
Reason: Alcohols show chain, position, and functional isomerism.
4. Which is an isomer of ethanol?
(a) CH₃OH
(b) CH₃OC₂H₅
(c) CH₃OCH₃
(d) C₂H₅OC₂H₅
✔ Correct Answer: (c) CH₃OCH₃ (Dimethyl ether)
Reason: Ethanol and CH₃OCH₃ are functional isomers (alcohol ↔ ether).
5. Of the following four characteristic groups, which is the characteristic group of secondary alcohol?
(a) –CH₂OH
(b) >CHOH
(c) –>COH
(d) –COOH
✔ Correct Answer: (b) >CHOH
Reason: Secondary alcohols have –OH attached to a carbon which is bonded to two other carbons.
6. Which one of the following is called wood spirit or wood naphtha?
(a) Ethyl alcohol
(b) Propyl alcohol
(c) Methyl alcohol
(d) Ethene
✔ Correct Answer: (c) Methyl alcohol
Reason: Methanol is called wood spirit because it was originally obtained by distillation of wood.
7. Carbinol is
(a) 1-Butanol
(b) Methyl alcohol
(c) Ethyl alcohol
(d) 2-Propanol
✔ Correct Answer: (b) Methyl alcohol
Reason: Methyl alcohol (CH₃OH) is commonly called carbinol.
8. The bacterial oxidation of ethanol of wine gives:
(a) Methylated spirit
(b) Absolute alcohol
(c) Vinegar
(d) Methanol
✔ Correct Answer: (c) Vinegar
Reason: Ethanol oxidized by Acetobacter bacteria produces acetic acid (vinegar).
9. Excessive intake of ethanol causes serious hepatic damage leading to a condition called:
(a) Diabetes
(b) Cirrhosis
(c) Cardiac myopathy
(d) Angina
✔ Correct Answer: (b) Cirrhosis
Reason: Chronic alcohol abuse can damage the liver, causing cirrhosis.
10. Which one of the following compound is obtained by the oxidation of primary alcohol with nascent oxygen?
(a) Alkanal
(b) Alkanone
(c) Ether
(d) Amine
✔ Correct Answer: (a) Alkanal
Reason: Oxidation of primary alcohols with nascent oxygen produces aldehydes (alkanals).
11. Which one of the following compound is obtained by the oxidation of secondary alcohols by [O]?
(a) Ketone
(b) Aldehyde
(c) Ether
(d) Amine
✔ Correct Answer: (a) Ketone
Reason: Secondary alcohols are oxidized to ketones by oxidizing agents.
12. The reaction of carboxylic acids with alcohols catalyzed by conc. H₂SO₄ is called:
(a) Neutralization
(b) Saponification
(c) Esterification
(d) Dehydration
✔ Correct Answer: (c) Esterification
Reason: Acid-catalyzed reaction of carboxylic acids with alcohols forms esters.
13. Which test is used to distinguish three types of alcohols?
(a) Lucas test
(b) Layer test
(c) Silver mirror test
(d) Baeyer’s test
✔ Correct Answer: (a) Lucas test
Reason: Lucas test (ZnCl₂ + HCl) differentiates primary, secondary, and tertiary alcohols.
14. Long chain carboxylic acid (fatty acid) reacts with glycerol to form triesters called:
(a) Triglycerides
(b) Triacyl glycerol
(c) Fats and Oils
(d) All of them
✔ Correct Answer: (d) All of them
Reason: Triesters of glycerol and fatty acids are called triglycerides, triacylglycerols, and fats/oils.
15. Which bond is cleaved when alcohols are converted to carbonyl compounds?
(a) Both O-H and C-H bond
(b) Both O-H and C-O bond
(c) C-O bond only
(d) O-H bond only
✔ Correct Answer: (a) Both O-H and C-H bond
Reason: Oxidation of alcohols involves breaking O-H and the hydrogen from C-H.
16. Which class of compounds is prepared by the cleavage of O-H bond of alcohols?
(a) Alkyl halides
(b) Amines
(c) Carbonyl compounds
(d) Esters
✔ Correct Answer: (a) Alkyl halides
Reason: Replacement of –OH with halogen (cleaving O-H) forms alkyl halides.
17. Which class of compounds is prepared by the cleavage of C-O bond of alcohols?
(a) Alkyl halides
(b) Amines
(c) Carbonyl compounds
(d) Esters
✔ Correct Answer: (a) Alkyl halides
Reason: Cleavage of C-O bond of alcohols gives alkyl halides.
18. Which class of compounds cannot be prepared by the cleavage of O-H bond of alcohols?
(a) Esters
(b) Alkanes
(c) Alkoxides
(d) Alkenes
✔ Correct Answer: (b) Alkanes
Reason: Cleaving O-H bond cannot form simple alkanes.
19. Which class of compounds is prepared by the cleavage of C-O bond of alcohols?
(a) Alkyl halides
(b) Amines
(c) Carbonyl compounds
(d) Esters
✔ Correct Answer: (c) Carbonyl compounds
Reason: Oxidation cleaves C-O bond to form aldehydes or ketones.
20. Which class of compounds is prepared by the cleavage of both C-O and C-H bond of alcohols?
(a) Alkyl halides
(b) Amines
(c) Carbonyl compounds
(d) Ethers
✔ Correct Answer: (c) Carbonyl compounds
Reason: Oxidation involves breaking C-H and C-O bonds, forming aldehydes/ketones.
21. Which type of reactions alcohols cannot undergo?
(a) Substitution
(b) Condensation
(c) Elimination
(d) Addition
✔ Correct Answer: (d) Addition
Reason: Alcohols do not undergo addition reactions; they mainly undergo substitution, condensation, and elimination.
22. Which of the following carbocations is the least stable?
(a) CH₃⁺
(b) (CH₃)₂CH⁺
(c) (CH₃)₃C⁺
(d) All
✔ Correct Answer: (a) CH₃⁺
Reason: Primary carbocation CH₃⁺ is least stable due to no alkyl group stabilization.
23. An alcohol can be converted into an alkene by:
(a) Addition
(b) Polymerization
(c) Substitution
(d) Dehydration
✔ Correct Answer: (d) Dehydration
Reason: Alcohols lose water (–OH and H) in the presence of acid to form alkenes.
24. 1-chlorobutane on reacting with alcoholic KOH gives:
(a) Butan-1-ol
(b) But-1-ene
(c) But-2-ene
(d) Butan-2-ol
✔ Correct Answer: (b) But-1-ene
Reason: Alcoholic KOH causes elimination (dehydrohalogenation) to form an alkene.
25. The salt of alcohol is called:
(a) Carboxylate
(b) Alkanoate
(c) Alkoxide
(d) None of these
✔ Correct Answer: (c) Alkoxide
Reason: Alcohol reacts with metals to form alkoxide salts (RO⁻M⁺).
26. The bacterial oxidation of ethanol of wine gives:
(a) Absolute alcohol
(b) Vinegar
(c) Methylated spirit
(d) Methanol
✔ Correct Answer: (b) Vinegar
Reason: Ethanol oxidized by Acetobacter bacteria produces acetic acid (vinegar).
27. 1-chlorobutane on reacting with alcoholic KOH gives:
(a) But-2-ene
(b) Butan-1-ol
(c) But-1-ene
(d) Butan-2-ol
✔ Correct Answer: (c) But-1-ene
Reason: Alcoholic KOH promotes elimination to give the 1-alkene.
28. The solubilities of higher alcohols decrease because they tend to resemble:
(a) Sugars
(b) Glucose
(c) Hydrocarbons
(d) Aldehydes
✔ Correct Answer: (c) Hydrocarbons
Reason: Long hydrocarbon chains in alcohols reduce polarity, decreasing water solubility.
29. Methanol is also known as:
(a) Wood spirit
(b) Wood naphtha
(c) Carbinol
(d) All of them
✔ Correct Answer: (d) All of them
Reason: Methanol is commonly called wood spirit, wood naphtha, and carbinol.
30. The first product of oxidation of primary alcohol is:
(a) An ester
(b) An aldehyde
(c) An acid
(d) A ketone
✔ Correct Answer: (b) An aldehyde
Reason: Primary alcohol oxidizes first to an aldehyde before further oxidation to carboxylic acid.
31. The condensation of excess of alcohol by concentrated sulphuric acid or alumina on heating to about 100-140ºC into simple symmetrical ether shows:
(a) Acidic nature of alcohols
(b) Basic nature of alcohols
(c) Amphoteric nature of alcohols
(d) Neutral nature of alcohols
✔ Correct Answer: (c) Amphoteric nature of alcohols
Reason: Alcohols show both acidic (–OH can donate H⁺) and basic (lone pair on O) behavior, demonstrating amphoteric nature.
Short Answer Questions

✏️ Smart Answers of Model Test Questions XII Chemistry Test # 8 Chapter # 7………… Alcohols and Ethers ✏️

Short Answer Questions

✏️ Answers of Short Questions of Alcohols and Ethers✏️

Q1. What are alcohols? How alcohols are classified? Define primary, secondary & tertiary alcohols. Write the structures & names of primary, secondary & tertiary alcohols of molecular formula C₅H₁₁OH (8 isomers).
Answer

🧪 Alcohols – Summary & Classification

✴️ Definition: Alcohols are aliphatic organic compounds containing one or more hydroxyl (–OH) groups attached to a saturated carbon atom.
👉 Derivatives of alkanes (replace H with –OH) or derivatives of water (replace H with alkyl group).

✴️ Monohydric Alcohols (Alkanols)

📌 Definition: Saturated aliphatic alcohols with one –OH group.
📌 General formula: CₙH₂ₙ₊₁OH or CₙH₂ₙ₊₂O
📌 Type formula: R–OH

🧪 Examples:
CH₃OH → Methanol
CH₃CH₂OH → Ethanol
CH₃CH₂CH₂OH → 1‑Propanol

✴️ Classification Based on Number of –OH Groups

🟢 Monohydric ➡️ One –OH group
🧪 Example: CH₃OH, C₂H₅OH, (CH₃)₂CHOH

🟢 Dihydric ➡️ Two –OH groups
🧪 Example: HO–CH₂–CH₂–OH (Ethylene glycol)

🟢 Trihydric ➡️ Three –OH groups
🧪 Example: HO–CH₂–CH(OH)–CH₂–OH (Glycerol)

🟢 Polyhydric ➡️ Four or more –OH groups
🧪 Example: Sorbitol, Mannitol

✴️ Classification Based on Nature of α‑Carbon

🟠 1° (Primary) Alcohols
➡️ –OH on carbon attached to one other C
🧪 Group: –CH₂–OH
🧪 Example: CH₃CH₂OH (Ethanol), CH₃CH₂CH₂OH (1‑Propanol)

🟡 2° (Secondary) Alcohols
➡️ –OH on carbon attached to two other C
🧪 Group: >CH–OH
🧪 Example: CH₃–CHOH–CH₃ (2‑Propanol)

🔴 3° (Tertiary) Alcohols
➡️ –OH on carbon attached to three other C
🧪 Group: ⪫C–OH
🧪 Example: (CH₃)₃COH (tert‑Butyl alcohol)

Draw possible isomers of C₅H₁₁OH
Answer

🟢 Primary (1°) Alcohols – 4 isomers

(–OH on a carbon attached to only one other carbon)

1️⃣ Pentan‑1‑ol → CH₃–CH₂–CH₂–CH₂–CH₂–OH
2️⃣ 2‑Methylbutan‑1‑ol → CH₃–CH(CH₃)–CH₂–CH₂–OH
3️⃣ 3‑Methylbutan‑1‑ol (Isoamyl alcohol) → CH₃–CH₂–CH(CH₃)–CH₂–OH
4️⃣ 2,2‑Dimethylpropan‑1‑ol (Neopentyl alcohol) → (CH₃)₃CCH₂OH

🟡 Secondary (2°) Alcohols – 3 isomers

(–OH on a carbon attached to two other carbon atoms)

5️⃣ Pentan‑2‑ol → CH₃–CH(OH)–CH₂–CH₂–CH₃
6️⃣ Pentan‑3‑ol → CH₃–CH₂–CH(OH)–CH₂–CH₃
7️⃣ 3‑Methylbutan‑2‑ol → CH₃–CH(OH)–CH(CH₃)–CH₃

🔴 Tertiary (3°) Alcohol – 1 isomer

(–OH on a carbon attached to three other carbon atoms)

8️⃣ 2‑Methyl‑2‑butanol (tert‑Amyl alcohol) → (CH₃)₂C(CH₂CH₃)OH

Q2. Give two examples of each of monohydric, dihydric and trihydric alcohols with their IUPAC names.
Answer

🧪 Examples of Alcohols (with IUPAC Names)

✴️ Monohydric Alcohols (Contain one –OH group)

1️⃣ Ethanol 🧬 Structure: CH₃–CH₂–OH 📘 IUPAC name: Ethanol
2️⃣ Propan‑1‑ol 🧬 Structure: CH₃–CH₂–CH₂–OH 📘 IUPAC name: Propan‑1‑ol

✴️ Dihydric Alcohols / Glycols (Contain two –OH groups)

1️⃣ Ethane‑1,2‑diol (Ethylene glycol) 🧬 Structure: HO–CH₂–CH₂–OH 📘 IUPAC name: Ethane‑1,2‑diol
2️⃣ Propane‑1,3‑diol 🧬 Structure: HO–CH₂–CH₂–CH₂–OH 📘 IUPAC name: Propane‑1,3‑diol

✴️ Trihydric Alcohols (Contain three –OH groups)

1️⃣ Propane‑1,2,3‑triol (Glycerol) 🧬 Structure: HO–CH₂–CH(OH)–CH₂–OH 📘 IUPAC name: Propane‑1,2,3‑triol
2️⃣ Butane‑1,2,4‑triol 🧬 Structure: HO–CH₂–CH(OH)–CH₂–CH₂–OH 📘 IUPAC name: Butane‑1,2,4‑triol

Q3. Write the equations for the following chemical processes:
(i) Reduction of acetic acid with LiAlH₄
(ii) Hydration of ethene with hot concentrated H₂SO₄
(iii) Oxidation of ethanol with acidified dichromate (Oxidation of alcohols)
(iv) Hydrolysis of diazonium salt
(v) Condensation of alcohols into ether
Answer

🧪 Equations of Chemical Processes

♻️ (i) Reduction of Acetic Acid with LiAlH₄ (reducing agent) into ethyl alcohol (1°‑alcohol)
⚖️Equation: CH₃COOH + 4[H] — (LiAlH₄/dry ether) → CH₃CH₂OH + 2H₂O (reduction)

♻️ (ii) Acid‑catalyzed Hydration of Ethene into ethanol with Hot Concentrated H₂SO₄ (E₁)
⚖️Equations: CH₂=CH₂ + H–OH —(Conc. H₂SO₄, hot/100°C)→ CH₃CH₂OH
OR
Ethene forms ethanol via ethyl hydrogen sulphate as intermediate.
⚖️Equations: CH₂=CH₂ + H₂SO₄ — (conc., hot) → CH₃CH₂OSO₃H + H₂O → CH₃CH₂OH + H₂SO₄

♻️ (iii) Oxidation of Ethanol with Acidified Dichromate first to aldehyde, then to acid
⚖️Equations: CH₃CH₂OH + [O] — (K₂Cr₂O₇ / H₂SO₄)/–H₂O → CH₃CHO + [O] — (K₂Cr₂O₇ / H₂SO₄)/–H₂O → CH₃COOH

♻️ (iv) Hydrolysis of Aryl Diazonium Salt by hot water into phenol
⚖️Equation: C₆H₅N₂⁺Cl⁻ + H₂O — Heat → C₆H₅OH + N₂↑ + HCl

♻️ (v) Condensation (intermolecular dehydration) of excess of Alcohols into Ether in acidic medium at 140°C
⚖️Equation: 2CH₃CH₂OH — (Conc. H₂SO₄, 140°C) → CH₃CH₂–O–CH₂CH₃ + H₂O

Q4. Explain the following scientific reason:
(i) Boiling point of ether is less than alcohol?
(ii) Alcohols are soluble in water.
(iii) Ethanol is liquid but ethyl chloride is gas at room temperature.
Answer

(i) Boiling point of ether is lower than alcohol 🔥
Ether does not form intermolecular hydrogen bonds, whereas alcohol does. Hence ether has a lower boiling point.

(ii) Alcohols are soluble in water 💧
Lower alcohols (up to three carbon atoms) form hydrogen bonds with water due to the presence of the polar –OH group.

(iii) Ethanol is liquid but ethyl chloride is gas at room temperature 🌡️
Ethanol forms strong intermolecular hydrogen bonds, while ethyl chloride cannot due to lack of polarized hydrogen (having only weak dipole–dipole forces). Therefore, ethanol is liquid and ethyl chloride is gas at room temperature.

Q5. Identify alcohol with two laboratory tests.
Answer

1) Identification of Alcohol by Sodium Metal Test ⚠️
Alcohol reacts with sodium metal to form sodium alkoxide with the liberation of hydrogen gas. The formation of brisk effervescence confirms the presence of an alcoholic (–OH) group.
Reaction: 2ROH + 2Na → 2RONa + H₂↑ (R = alkyl group)

2) Identification of Alcohol by Ester Test 🍍
When an alcohol is heated with acetic acid in the presence of concentrated sulphuric acid, an ester is formed. The appearance of a pleasant fruity smell indicates the presence of an alcoholic group.
Reaction: C₂H₅OH + CH₃COOH → CH₃COOC₂H₅ (fruity smell) + H₂O

Q6. What is Lucas reagent? Describe its use to distinguish between primary, secondary and tertiary alcohol.
Answer

✨Lucas reagent: a mixture of concentrated HCl and anhydrous ZnCl₂.
✨Purpose: Distinguishing primary, secondary, and tertiary alcohols based on the rate of formation of alkyl chloride (turbidity).
✨Basis: Faster turbidity = higher degree of alcohol

✨Order of reactivity of Alcohols: 3° > 2° > 1°⚡
✨Order of reactivity of Halogen acids: HI > HBr > HCl
(HCl reacts with less reactive alcohols only in presence of ZnCl₂)

✨Lucas Test Observations & Equations

⚡ (a) Tertiary alcohol 🚀
➡️Observation: Immediate turbidity / insoluble oily layer
➡️Condition: Room temperature
➡️Equation: R₃COH + HCl → R₃CCl + H₂O

⚡ (b) Secondary alcohol ⏱️
➡️Observation: Turbidity after 5–10 minutes
➡️Condition: Room temperature
➡️Equation: R₂CHOH + HCl → R₂CHCl + H₂O

⚡ (c) Primary alcohol 🔥
➡️Observation: No turbidity at room temperature
➡️Condition: No immediate reaction, occurs only on heating
➡️Equation: RCH₂OH + HCl → RCH₂Cl + H₂O (ZnCl₂, heat)

Q7. What is oxonium ion? How can ether form oxonium ion?
Answer

Oxonium Ion and its Formation 🧪

Oxonium ion is a positively charged ion in which the oxygen atom forms three bonds and carries a +1 formal charge (a trivalent oxygen cation). Its general formula is R₃O⁺ (R = H or alkyl group). The simplest oxonium ion is hydronium ion (H₃O⁺).

Formation of Oxonium Ion from Ether ⚡

Ethers act as weak bases due to the presence of lone pair of electrons on the oxygen atom. When an ether reacts with a strong acid, it accepts a proton to form an oxonium ion (oxonium salt).

Equation: R–Ӧ:–R′ + H⁺ — H₂SO₄ (conc.) → R– Ӧ⁺H–R′
Example Equation: R–Ӧ:–R′ — H⁺/HCl (conc.) → [R– Ӧ⁺H–R′]Cl⁻
Example Equation: R–Ӧ:–R′ — H⁺/H₂SO₄ (conc.) → [R– Ӧ⁺H–R′]HSO₄⁻

Short Answer Questions

✏️ Smart Answers of Descriptive Questions ✏️

Q1. Starting from Grignard reagent how is primary, secondary and tertiary alcohol prepared?
Answer

Preparation of Three Types of Alcohols Using Grignard Reagent via its nucleophilic addition reaction with carbonyl compounds 🧪

Grignard reagents (RMgX) react with carbonyl compounds (formaldehyde, higher aldehydes like acetaldehyde and ketones like acetone) via nucleophilic addition to produce different types of next higher alcohols. The type of alcohol depends on the carbonyl compound used. The resulting alcohol has one more carbon atom than the Grignard reagent. (Grignard reagent acts as a nucleophile, attacking the electrophilic carbon of the carbonyl group forming magnesium alkoxide intermediate, which is converted to alcohol by acidic hydrolysis).

⚖️ General Reaction: Grignard + carbonyl → magnesium alkoxide (intermediate adduct) → hydrolysis → alcohol

Formaldehyde (H–CHO) → Primary Alcohols 🟢

Reaction: RMgX + H–CHO → [R–CH₂OMgX] → R–CH₂OH (after hydrolysis)

Higher aldehydes (e.g., acetaldehyde CH₃CHO) → Secondary Alcohols 🟡

Reaction: RMgX + R′–CHO → [R–CH(OMgX)–R′] → R–CH(OH)–R′ (after hydrolysis)

Ketones (e.g., acetone (CH₃)₂CO) → Tertiary Alcohols 🔴

Reaction: RMgX + R′₂C=O → [R–C(OMgX)–R′₂] → R–C(OH)–R′₂ (after hydrolysis)

📌 Summary

🟢 Primary alcohol: RMgX + H–CHO → R–CH₂OH
🟡 Secondary alcohol: RMgX + R′–CHO → R–CH(OH)–R′
🔴 Tertiary alcohol: RMgX + R′₂C=O → R–C(OH)–R′₂

Q2. Write the equations for the following possible conversions:
(i) Ethyl alcohol to diethyl ether
(ii) Phenol into benzoquinone
(iii) Ethyl bromide to ethanol
(iv) 2°-alcohol to carboxylic acid
(v) Ethanol into acetic acid
(vi) Ethyl alcohol into ethyne
(vii) Ethene into ethanol
Answer

✨Equations for Conversions

♻️ (i) Ethanol → Diethyl ether 🔥 (Condensation (intermolecular dehydration) of excess of Ethyl alcohol into diethyl ether in acidic medium at 140°C)
⚖️Equation: 2CH₃CH₂OH — (conc. H₂SO₄, 140°C) → CH₃CH₂–O–CH₂CH₃ + H₂O

♻️ (ii) Phenol → Benzoquinone ⚡ (Oxidation of Phenol into yellow coloured dicarbonyl compound benzoquinone)
⚖️Equation: C₆H₅OH + [O] — K₂Cr₂O₇/H⁺ → C₆H₄O₂ (oxidation)

♻️ (iii) Ethyl bromide → Ethanol 💧 (Sɴ of Br group of ethyl bromide by –OH group of aqueous KOH giving ethyl alcohol)
⚖️Equation: CH₃CH₂ᵟ⁺Brᵟ⁻ + K⁺OH⁻ (aq) — Sɴ₂ → CH₃CH₂OH + KBr

♻️ (iv) 2° Alcohol → Ketone → Carboxylic acid 🔄 (Oxidation of 2°-alcohol to lower previous carboxylic acid)
⚖️Equation: R₂CHOH + [O] — K₂Cr₂O₇/H⁺ → R₂C=O + 4[O] — K₂Cr₂O₇/H⁺ → RCOOH (strong oxid.)

♻️ (v) Ethanol → Acetic acid 🍎 (Oxidation of Ethanol with Acidified Dichromate first to aldehyde, then to acid)
⚖️Equations: CH₃CH₂OH + [O] — (K₂Cr₂O₇/H₂SO₄)/–H₂O → CH₃CHO + [O] — (K₂Cr₂O₇/H₂SO₄)/–H₂O → CH₃COOH

♻️ (vi) Ethyl alcohol → Ethyne 🔥 (Dehydration, Halogenation, Double Dehydrohalogenation)
CH₃CH₂OH — H₂SO₄/170°C/–H₂O → CH₂=CH₂ (Acid-catalyzed dehydration)
CH₂=CH₂ + Br₂ — CCl₄ → BrCH₂–CH₂Br (Halogenation)
BrCH₂–CH₂Br + 2KOH — Alcohol/Heat → CH≡CH + 2KBr + 2H₂O (Double Dehydrohalogenation)

♻️ (vii) Ethene → Ethanol 💧 (Acid-catalyzed Hydration of ethene into ethanol with Conc. via E₁ mechanism)
⚖️Equation: CH₂=CH₂ + H₂O — (H₂SO₄, 100°C) → CH₃CH₂OH

Q3. Differentiate between alcohol and phenol on the basis of:
(i) Solubility in water
(ii) Boiling point
(iii) Acidic character
Answer

✨ (i) Water solubility 💧
➡️Alcohol: Readily soluble due to hydrogen bonding with water
➡️Phenol: Less soluble; aromatic ring reduces water solubility

✨ (ii) Boiling Point 🔥
➡️Alcohol: Generally lower than phenols
➡️Phenol: Higher boiling point due to stronger hydrogen bonding

✨ (iii) Acidic Character / Acidity ⚡
➡️Alcohol: Weak acid (higher pKₐ)
➡️Phenol: Stronger acid (lower pKₐ)

Q5. Enlist the commercial applications of alcohol, phenol and ether.
Answer

Commercial Applications of Alcohols, Phenols, and Ethers ✨

Uses of Alcohols 🍾

Uses of Methanol (CH₃OH) 🔹
➡️ Perfumes, dyes, drugs
➡️ Antifreeze solution
➡️ Solvent for varnishes, paints, polishes
➡️ Production of formaldehyde / formalin
➡️ Mixed with ethanol → Methylated Spirit (denatured alcohol)

Uses of Ethanol (C₂H₅OH) 🔹
➡️ Raw material for organic compounds: acetone, acetic acid, esters, chloroform, ether, ethanol, resins, varnishes
➡️ Base for perfumes (Deodorized ethanol)
➡️ Low-temperature thermometric liquid
➡️ Petrol additive (octane improver)
➡️ Component of alcoholic beverages: spirits, wine, beer

Uses of Rubbing Alcohol (Isopropyl alcohol in water) 🔹
➡️ Used as antiseptic

Uses of Phenol (C₆H₅OH) ⚡

➡️ Antiseptic and disinfectant
➡️ Manufacturing of soaps, plastics, ointments, lozenges
➡️ Preparation of picric acid and phenolphthalein
➡️ Ink preservative

Uses of Ethers (R–O–R) 💧

➡️ Solvent in manufacturing waxes, gums, resins, oils
➡️ Solvent for Wurtz reaction & Grignard reagent preparation in the form of Diethyl ether

Q6. How do you prepare alcohol from carbonyl compounds, alkenes & esters?
Answer

Preparation of Alcohols from Carbonyl Compounds, Alkenes & Esters ✨

Preparation of Alcohols By the reduction of Carbonyl Compounds i.e. Aldehydes and ketones (Hydrogenation across >C=O)🔥

General Rule: Aldehydes → Primary alcohols
Ways of Reduction:
➡️ Catalytic reduction by H₂ gas using catalyst like Ni, Pt or Pd
➡️ Chemical reduction by nascent hydrogen using reducing agents like lithium aluminum hydride (LiAlH₄) or sodium borohydride (NaBH₄)

R–CHO + H₂ → R–CH₂OH (Ni/Pt/Pd, high temp)
or
R–CHO + [H] → R–CH₂OH (LiAlH₄ / NaBH₄)

Ketones → Secondary alcohols
R₂C=O + H₂ → R₂CHOH (Ni/Pt/Pd, high temp)
or
R₂C=O + [H] → R₂CHOH (LiAlH₄ / NaBH₄)

Preparation of Alcohols By Acid-catalyzed hydration of alkene 💧

Alkene + H₂O → Alcohol (conc. H₂SO₄, heat)
Example: CH₂=CH₂ + H₂O → CH₃CH₂OH

From Esters Using Grignard Reagent ⚡

Ester + RMgX → Ketone intermediate → Reacts with another RMgX → Tertiary alcohol
Equation (general):
RCOOR′ + RMgX → R₂C(OMgX)R′ → R₂C(OH)R′ (after hydrolysis)

From Esters Using LiAlH₄ 🔹

Ester + LiAlH₄ → Primary alcohols (two molecules of alcohol may form)
Equation:
RCOOR′ + 4[H] → RCH₂OH + R′OH

🧠 Key Points for Exams

Aldehydes → 1° alcohol
Ketones → 2° alcohol
Alkenes → Hydration → Alcohol
Ester + Grignard → 3° alcohol
Ester + LiAlH₄ → 1° alcohol

 































































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