Have you ever wondered the things like soft drinks, perfumes, antiseptics, and disinfectants that we use in our daily lives come from? So, all of these come from oxygen-containing organic compounds like alcohol, such as ethanol used in soft drinks, beverages, and sanitizers, while Phenols are used in antiseptics and disinfectants, and Ether is used in the manufacturing of perfumes. These alcohol phenol and ether ncert solutions discusses three important classes of compounds that feature oxygen-containing organic compounds which are widely used in the medical industry and in daily life.
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NCERT Solutions for Class 12 Chemistry Chapter 7 Download PDF
NCERT Solutions for Class 12 Chemistry Chapter 7 (Intext Questions Exercise)
NCERT Solutions for Class 12 Chemistry Chapter 7 (Exercise Questions with Answers)
Class 12 Chemistry NCERT Chapter 7: Higher Order Thinking Skills (HOTS) Questions
Approach to Solve Questions of Class 12 Chemistry Chapter 7
Topics and Subtopics Covered in the NCERT Textbook
What Extra Should Students Study Beyond the NCERT for JEE?
NCERT Solutions Class 12 Chemistry Chapter-Wise
NCERT Solutions for Class 12 Subject-wise
NCERT Books and NCERT Syllabus
Alcohols, Phenols and Ethers
The NCERT Solution for Class 12 Chemistry explains various concepts that we observe in our daily lives. When the OH group replaces the hydrogen atom in aliphatic hydrocarbons, Alcohols are formed same goes for phenols when the OH group replaces the hydrogen of aromatic hydrocarbons, then Phenols are formed while Ethers are formed when alkoxy (R-O) or aryloxy (Ar-O) group substitutes the hydrogen atom in hydrocarbons. These NCERT Solutions provide a structured approach to understanding the classification, properties, preparation, and reactions. Students will learn about important concepts like nomenclature, structure, and uses of organic compounds containing oxygen. This article includes some higher-order thinking skills (HOTS) questions and approach to solve questions.
NCERT Solutions for Class 12 Chemistry Chapter 7 Download PDF
Students can download the NCERT Solutions for Class 12 Chemistry Chapter 7 PDF for free. These solutions are designed to help you understand the fundamental concepts and solve textbook questions with ease.
NCERT Solutions for Class 12 Chemistry Chapter 7 (Intext Questions Exercise)
Detailed alcohol phenol and ether ncert solutions for intext questions are given below. Download the free PDF and prepare for your exams with confidence.
NCERT Solutions for Class 12 Chemistry Chapter 7 (Exercise Questions with Answers)
Given below the clear and simple solutions to all exercise questions of Class 12 Chemistry Chapter 7. Download and study these answers to prepare well for exams.
Propanol forms intermolecular H-bonds because of the presence of -OH group while butane cannot. To break these bonds, extra energy will be required. This causes a higher boiling point for propanol as compared to butane.
Alcohols form hydrogen bonds with water due to the presence of –OH group whereas hydrocarbons cannot. Due to this inter molecular hydrogen bonding, alcohols are more soluble in water.
Hydroboration-oxidation reaction also called HBO reaction is the addition of borane followed by oxidation to produce alcohol.
Eg: Hydroboration-oxidation reaction of propene. In this reaction, propene reacts with diborane (BH3)2 to form trialkyl borane. This addition product is oxidized by hydrogen peroxide in the presence of aqueous sodium hydroxide to form propan-1-ol.
Due to inter-molecular H bonding in para-nitrophenol, it gets tightly bonded with water. But ortho nitrophenol has intra-molecular H bonding and hence is steam volatile.
Cumene (isopropylbenzene) is oxidised in the presence of air to form cumene hydroperoxide. On treating with dilute acid it is converted to phenol and acetone.
1. Phenol reacts with sodium to give sodium phenoxide, liberating hydrogen gas.
2. Phenol reacts with sodium hydroxide to give sodium phenoxide and water.
Phenol is more acidic than ethanol. This is because phenol after losing a proton becomes phenoxide ion which is highly stable due to resonance whereas ethoxide ion does not.
Ortho-nitrophenol is more acidic than ortho- methoxyphenol . The presence of the nitro group, which is an electron withdrawing group, at the ortho position decreases the electron density in the O-H bond. Also, the o- nitrophenoxide ion formed after the loss of protons is stabile due to resonance. Hence, ortho nitrophenol is a stronger acid. Whereas the methoxy group is an electron-releasing group. Thus, it increases the electron density in the O-H bond.
The -OH group is an electron-donating group (EDG). Thus, it increases the electron density in the benzene ring in the resonance structure of phenol. As a result, the benzene ring is activated towards electrophilic substitution.
Kolbe’s reaction: Phenol with carbon dioxide under pressure followed by treating the product with sulphuric acid produces Ortho-hydroxybenzoic acid (salicylic acid). Phenoxide ion generated is more reactive than phenol towards electrophilic aromatic substitution. Hence, it undergoes electrophilic substitution with carbon dioxide, a weak electrophile.
On treating phenol with chloroform in the presence of sodium hydroxide, a –CHO group is introduced at the ortho position of the benzene ring. This reaction is known as Reimer - Tiemann reaction
Alcohols undergo dehydration (removal of a molecule of water) to form alkenes on treating with a protic acid. Ethanol undergoes dehydration by heating it with concentrated sulphuric acid at 443 K.
Ethanol undergoes intermolecular hydrogen bonding due to the presence of -OH group. Therefore, extra energy is required to break those hydrogen bonds. Whereas methoxymethane does not make H-bonds and hence ethanol has a higher boiling point than methoxymethane.
Williamson synthesis involves $S_N2$ attack by alkoxide ion on a primary alkyl halide. But if secondary or tertiary alkyl halides are taken then alkenes would be produced because elimination would take place. This is because alkoxides are nucleophiles as well as strong bases.
The formation of ethers by dehydration of a primary alcohol is an SN2 reaction. In case of secondary or tertiary alcohols, the alkyl group is hindered and hence elimination dominates substitution. Therefore alkenes are formed in place of ethers.
Due to the +R effect of the alkoxy group, it increases the electron density of the benzene ring pushing electrons into the ring making the benzene ring activated towards electrophilic substitution reactions.
The above resonating structures shows that the electron density increases more at the ortho and para positions as compared to the meta positions. Hence, the alkoxy group directs the incoming substituents to ortho and para positions in the benzene ring.
Give a mechanism for this reaction.
(Hint : The secondary carbocation formed in step II rearranges to a more stable tertiary carbocation by a hydride ion shift from 3rd carbon atom.
Answer :
Mechanism for the reaction 3-methylbutan-2-ol is treated with HBr
Class 12 Chemistry NCERT Chapter 7: Higher Order Thinking Skills (HOTS) Questions
Selected Higher Order Thinking Skills questions from Chapter 7 to strengthen your concepts are given below. These NCERT Solutions for Class 12 Chemistry Chapter 7 Alcohols, Phenols and Ethers will help you practise advanced problems and improve exam readiness.
Question 1. Which one of the following, with HBr, will give a phenol?
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Question 3. Given below are two statements: Statement I:
The acidic strength of monosubstituted nitrophenol is higher than phenol because of the electron-withdrawing nitro group. Statement II:
o-nitrophenol, m-nitrophenol and p-nitrophenol will have the same acidic strength as they have one nitro group attached to the phenolic ring
In light of the above statements, choose the most appropriate answer from the options given below:
Both Statement I and Statement II are incorrect.
Statement I is correct, but Statement II is incorrect.
Statement I is incorrect, but Statement II is correct.
Both Statement I and Statement II are correct.
Answer:
Electron-withdrawing group, O-Phenol increases its acidic strength
Statement I is correct
Now, the pKa values of nitro-substituted Phenols are given below:
Thus acidic strength of nitrophenols is
Para > Ortho > Meta
Hence, statement I is correct while statement II is incorrect
Hence, the correct answer is option (2).
CBSE Class 12th Syllabus: Subjects & Chapters
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Approach to Solve Questions of Class 12 Chemistry Chapter 7
Alcohols, Phenols and Ethers NCERT Solutions is an essential study material that is required for all students preparing for Class 12 board exams as well as competitive exams. Here are some tips that students can follow to effectively solve questions:
1. Understand about nomenclature
Questions related to nomenclature are often asked in exams, hence knowing the IUPAC naming rules for alcohols, phenols, and ethers becomes important. For ethers, name the smaller alkyl group as a prefix, followed by the main chain
2. Learn about methods of preparation
Preparation reactions of Alcohols, Phenols, and Ethers from haloalkanes, alkenes, carbonyl compounds, etc. Learn about reagents and conditions, like the hydration of alkenes and Williamson synthesis for ethers
3. Physical Properties
Compare boiling points, solubility, and hydrogen bonding.
4. Reactivity Order and Mechanisms:
Questions related to reaction mechanisms play a very important role and are often asked in exams. Practice reaction mechanisms like dehydration of alcohols, oxidation, and acidic behaviour of phenols.
5. Practice Questions:
Students can refer to the solved examples in the textbook and then solve the in-text questions. Students can also access the NCERT Solutions for Class 12 Chemistry Chapter 7 PDF for quick revision of the concepts.
Topics and Subtopics Covered in the NCERT Textbook
All the topics and subtopics covered in the NCERT Class 12 Chemistry Chapter 7 Alcohols, Phenols and Ethers are listed below:
7.1 Classification
7.1.1 Alcohols - Mono, Di, Tri, or Polyhydric Alcohols
7.1.2 Phenols- Mono, Di, and Trihydric Phenols
7.1.3 Ethers
7.2 Nomenclature
7.3 Structures of Functional Groups
7.4 Alcohols and Phenols
7.4.1 Preparation of Alcohols
7.4.2 Preparation of Phenols
7.4.3 Physical Properties
7.4.4 Chemical Reactions
7.5 Some Commercially Important Alcohols
7.6 Ethers
7.6.1 Preparation of Ethers
7.6.2 Physical Properties
7.6.3 Chemical Reactions
What Extra Should Students Study Beyond the NCERT for JEE?
Students need to focus on important concepts and reactions according to the table given below:
Q: What are the main types of alcohols discussed in Class 12 Chemistry Chapter 7?
A:
Chapter 7, discusses three types of alcohols primary, secondary, and tertiary alcohols. Primary alcohols have the hydroxyl group attached to a carbon atom that is bonded to only one other carbon. Secondary alcohols are connected to two other carbons, while tertiary alcohols have the hydroxyl group on a carbon that is connected to three other carbons.
Q: How are phenols different from alcohols?
A:
Phenols are compounds where the hydroxyl group is directly bonded to an aromatic benzene ring, whereas alcohols have the OH group attached to aliphatic carbon chains. This structural difference leads to varying physical and chemical properties.
Q: What is the significance of the hydroxyl group in alcohols and phenols as discussed in NCERT Class 12 Chemistry Chapter 7 Alcohols, Phenols and Ethers ?
A:
The hydroxyl group is crucial as it imparts unique properties to alcohols and phenols. It makes these compounds polar, allowing them to form hydrogen bonds with water, which contributes to their solubility in water.
Q: What methods are commonly used for the preparation of alcohols?
A:
Common methods for preparing alcohols include fermentation, which converts sugars into ethanol; reduction of carbonyl compounds using reducing agents and hydration of alkenes in the presence of an acid.
Q: What are the hazards of alcohols, phenols, and ethers?
A:
Hazards of alcohols, phenols, and ethers:
Alcohols can be harmful if ingested, inhaled, or absorbed through the skin.
Phenols can cause skin and eye irritation, and these are also harmful if inhaled.
Ethers can cause dizziness and respiratory irritation. They can also form explosive peroxides if stored improperly.
If you want to improve the Class 12 PCM results, you can appear in the improvement exam. This exam will help you to retake one or more subjects to achieve a better score. You should check the official website for details and the deadline of this exam.
SASTRA University commonly provides concessions and scholarships based on merit in class 12 board exams and JEE Main purposes with regard to board merit you need above 95% in PCM (or on aggregate) to get bigger concessions, usually if you scored 90% and above you may get partial concessions. I suppose the exact cut offs may change yearly on application rates too.
CBSE generally forwards the marksheet for the supplementary exam to the correspondence address as identified in the supplementary exam application form. It is not sent to the address indicated in the main exam form. Addresses that differ will use the supplementary exam address.
To find Class 12 Arts board papers, go to the official website of your education board, then click on the Sample Papers, Previous Years Question Papers(PYQ) or Model Papers section, and select the Arts stream. You will find papers for the various academic year. You can then select the year of which you want to solve and do your practice. There are many other educational websites that post pyqs on their website you can also visit that.
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