NCERT Exemplar Class 12 Chemistry Chapter 11 Solutions: Alcohols, Phenols and Ethers
NCERT Exemplar Class 12 Chemistry Solutions Chapter 11: Alcohol, phenols, and Ethers are a fundamental study material for students preparing for CBSE Board exams. This Exemplar book contains questions from various sections that will help you learn the concepts from scratch to advanced level. NCERT Exemplar Class 12 Chemistry solutions for chapter 11 provides you a brief overlook of the concept of alcohols, phenols, and ethers. These questions are known to be repeated over the years and still pose a chance to come in the upcoming exams.
There are a total of 74 Problems in NCERT Exemplar Book that are isolated into 5 sections such as MCQs, SA, Matching Types, Assertion and Reason, and Long answer type questions. With the help of these Exemplar problems you will be able to grasp knowledge on all the aspects like a method of preparation of Alcohols, phenols, and ethers, physical and chemical properties involved, different chemical reactions, and their applications in various fields, etc.
Instasolv has come up with a brilliantly plotted practice guide for the students. Problems in NCERT Exemplar Book are framed after thorough reviews of the subject experts, in such a way that will aid you to become proficient in all the important topics associated with it. Regular practice by Instasolv assures your success in various competitions and other graduate-level entrance exams.
Important Topics for NCERT Exemplar Class 12 Chemistry Solutions Chapter 11: Alcohols, Phenols, and Ethers
After studying this NCERT Exemplar Class 12 Chemistry Solutions Chapter 11: Alcohols, Phenols, and Ethers students will get over the knowledge of all the properties of alcohols, phenols, and ethers. You will also get used to naming their IUPAC nomenclature.
Let’s have a look at some of the important concepts of this chapter.
An organic compound that contains at least one hydroxyl group (-OH) attached with saturated carbon atoms is termed as alcohol. Alcohol is nothing. In fact, they are derived from the waters. The hydrogen atom is replaced by the alkyl group, generally represented by R in organic structures. Alcohols are the most common organic compounds which have several uses in our daily life. They are used in making perfumes, and also help in the synthesis of other organic compounds. They are the most abundant used compounds in the chemical industry.
For Example – Methanol and Ethanol
- Classification of alcohols:
Alcohols are classified into three different categories named as:
- Primary Alcohols.
- Secondary Alcohols.
- Tertiary Alcohols.
- Primary Alcohols- Hydroxyl group attached with the primary carbon atom of alkyl group.
Formula – “–CH2OH”
- Secondary Alcohols- Hydroxyl group attached with the secondary carbon atom of alkyl group.
Formula – “–CHR-OH”
- Tertiary Alcohols – Hydroxyl group attached with the primary carbon atom of alkyl group.
Phenols are the organic compounds in which hydroxyl functional groups are attached with carbon atoms of aromatic rings. In other words, they are also termed as monohydroxybenzene (C6H5OH), also benzenol or carbolic acid.
Phenols are quite similar to alcohols but they form stronger hydrogen bonding. As far as solubility is concerned, phenols are more soluble in water compared to alcohol. higher boiling As you know phenol forms hydrogen bonding. This ability makes its boiling point more than alcohol. They are colourless liquids. Phenols possess white solids when they are subjected to room temperature.
Apart from these, phenols are also used as intermediate in industrial synthesis, used as household products- as a disinfectant for house cleaning purposes. They are also used for surgical purposes and by the way phenol is the first surgical antiseptic.
- Synthesis of Phenols
Usually, we have seen that almost all types of phenols are used today, produced by benzene(either by hydrolysis of chlorobenzene or oxidation of isopropyl benzene). Let’s see both types:
Hydrolysis of chlorobenzene(the dow process)
This process is one of the best processes of the formation of phenols. In this chlorobenzene is hydrolyzed in the presence of sodium base at almost 350-degree Celsius temperature leads to the formation of phenoxide ions which are further acidified into phenols.
Oxidation of isopropyl benzene
When benzene is subjected to propylene in the presence of an acidic catalyst it gives cumene. After oxidation, it gives a cumene hydroperoxide, which is further acidified and leads phenols and acetone.
When an oxygen atom is bounded among the two alkyl or aryl groups atoms are considered as ether groups, and the organic compounds that contain ether groups are called Ethers. They are quite similar to alcohol. Both alcohols are similar in the context of water. As you know, in alcohols one hydrogen atom of water is replaced by an alkyl group, whereas in ethers both of the hydrogen is replaced by the alkyl or aryl groups.
- Physical properties of Ethers
Due to lack of hydroxyl groups, ethers do not make hydrogen bonding with each other. Oxygen atoms in ethers do have non-bonded electron pairs, however, they form hydrogen bonding with the other molecules such as alcohols and amines. This ability to form hydrogen bonding makes ethers good solvents among different organic compounds.
Because ethers do not possess hydrogen bonding with each other, they have less boiling points compared to alcohols with similar molecular weights.
For Example, Diethyl ether and n-butyl alcohol have similar molecular weights, yet they do not have the same boiling points. Diethyl ether has 35-degree celsius whereas 118-degree Celsius is the boiling point of n- butyl alcohol with the similar molecular weights of 74.
- · Synthesis of Ethers:
Ethers are usually prepared with the help of alcohol and their conjugate bases. Here are the two most prominent methods of formation of ethers. Let’s have a look at these two types.
- Williamson synthesis.
- By Bimolecular dehydration of alcohols.
Apart from these ethers are also significant in the medical fields. Ethyl ether was the first ether compound of its family used as anaesthetics. Ethers are highly flammable, this makes ethers best among the less flammable anaesthetics like nitrous oxide (N2O), and halothane (CF3―CHClBr). It is also used for pain-relieving purposes(Codeine- a pain-relieving drug)
Discussion of exercises of NCERT Exemplar Class 12 Chemistry Solutions Chapter 11
- As discussed earlier, NCERT Exemplar Class 12 Chemistry Solutions Chapter 11 has 74 NCERT Exemplar problems are segregated into 5 sections viz. MCQs, SA, Matching type, Assertion and reason, and Long answer type questions which cover all the important aspects of the entire chapter.
- The 1st section is of multiple-choice questions type. It is divided into two types: MCQ1 & MCQ2. MCQ1 contains 16 questions whereas 5 questions are there in type 2. You need to pick out the one correct option among 4 options in these types of questions. Topics covered in this section are Properties of alcohols, Nomenclature, Acidic and Basic properties of alcohols, Chirality, etc.
- The 2nd set of questions are of short answer type questions. This section has 34 NCERT Exemplar problems. For solving these questions you need to have a piece of knowledge on topics such as Nomenclature, conversion of alcohols, the solubility of alcohols, polarity, chemical reactions involved, its applications in medical fields, etc.
- The next set of questions are matching types, where you need to match the columns. This section has 4 questions for which you should have a pretty knowledge of the several named reactions like Williamson synthesis, Reimer Tiemann reaction, Kolbe’s reaction.
- The next set of questions are of assertion and reason type. It has 10 NCERT Exemplar problems. In the following questions, a statement of assertion followed by a statement of reason is given. Questions are based on the boiling points, solubility, and acidity of alcohols, phenols, and, ethers, etc.
- The 5th set of questions involves long answers with 4 Exemplar problems, and will judge your understanding of the mechanism of HI with methoxy benzene, and also knowledge about biocatalyst. A question from its medical applications also.
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- Solving NCERT Exemplar Class 12 Chemistry Solutions Chapter 11: Alcohols, Phenols, and Ethers by Instasolv can be an ultimate option for the students, aspiring their careers especially in the engineering field.
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