12th Class Chemistry Chapter 11 Alcohols Phenols and Ethers Short Questions Answer

Chemistry short QA

12th Class Chemistry Chapter 11 Alcohols, Phenols and Ethers Short Questions Answer

1.What is the similarity of water with alcohols phenols and ethers?
2.Define and give examples for each of monohydric dihydric and trihydric alcohols?
3.How primary secondary and tertiary alcohols are different from each other in structures?
4.How water gas is converted into methyl alcohol scale?
5.What is fermentation process for manufacture of alcohols?Give the necessary conditions?
The process of conversion of starch and sugar to ethyl alcohol under the influence of yeast is called fermentation.There should be proper aeration solution should be dilute and there should be no preservative for fermentation purposes.
6.What is raw material for the manufacture of ethyl alcohol on the commercial scale?
Ethyl alcohol can be prepared by the fermentation of cane juice beets dates molasses and fruit juices.These substances have fermentable sugars. Moreover ,Potatoes,rice,barley and maize contain starch which give us alcohol on fermentation.
7.Absolute alcohol cannot be prepared by fermentation process.Why?
Absolute alcohol cannot be prepared by fermentation process.Actually 14% alcohol is obtained in fermentation process which can be concentrated upto 95%.95% alcohol forms azeotropic mixture which cannot be futher concentrated by distillation.Anyhow lime is used to concentrate alcohol further.
8.What is rectified spirit commercial alcohol and absolute alcohol?
95% ethyl alcohol is called rectified spirit.It is also called commercial alcohol.It is converted to 99.9% alcohol by distilling it in the presence of CaO.This is called absolute alcohol.
9.What do you mean by denaturing of alcohol?
Alcohol is denatured by the addition of 10% methanol.In this way it becomes poisonous and becomes unfit for drinking purpose.This is called methylated spirit.A small quantity of pyridine or acetone may be added for denaturing.
10.Ethyl alcohol is a liquid while methyl chloride is a gas.Given reason?
11.Why ethanol has higher boiling point than diethyl ether but less than water?
Ethanol has a hydrogen bonding among the molecues.For this reason it has a higher boiling point than that of ether.Ether is a non-polar molecule and there is no hydrogen bonding in it.The extent of H-bonding in H2O is much greater than alcohol.
12.Why alcohol is miscible with water?
Water has two partial positive hydrogen atoms and alcohol have one.So there is hydrogen bonding in them which makes them miscible.
13.What is esterification?Give the reaction comditions for this reaction?
The reaction of carboxylic acids with alcohols in the presence of an acid as a catalyst give us esters and water.This is a reversible reaction and is called esterification.
14.How the strong strong oxidizing agents affects the primary and secondary alcohols?
15.Ethanol gives different products with conc.H2SO4 under different conditions?
16.What are the dehydrogenation products of primary and secondary alcohols in the presence of copper?
When primary and secondary alcohols are heated at 300ᵒCin the presence of copper primary alcohols are converted into aldehydes secondary alcohols into ketones and tertiary alcohols into alkenes.
17.What is Lucas test which is used to distinguish between primary secondary and tertiary alcohols?
When primary secondary  and  tertiary alcohols are treated with HCI in the presence of ZnCI2  tertiary alcohols give the oily liquids immediately.Secondary alcohols give  the reaction within 5-10 minutes and primary alcohols do not give the  reaction at room temperatre.
18.How haloform reation can be used to distinguish between certain alcohols?
All those  primary or secondary alcohols which on oxidation give  methyl aldehde or methyl ketones give the haloform reaction,e.g.C2H5 – OH-,CH3-CH-CH3etc.give the haloform reaction.CH3CH2OH gives  CH3CHO and CH3CH(OH)CH3 gives  CH3COCH3 which  further react to produce CHI3.
19.How halodoform test can be used to distinguish between methyl alcohol and ethyl alcohol?
Ethyl alcohol upon ocidation give CH3CHO.It is an aldehyde having- CH3 with – C = O group  and can give the iodoform reaction.Methyl alcohols give formaldehyde.It does not have CH3 group.So it will not give haloform reaction.
20.Give the uses of methyl alcohol?
Methyl alcohol is used as a solvent for oils fats paints and varnishes.It is anitifreeze for automobile radiators.It is used for the denaturing of alcohols.It is used for the manufacture of formaldehyde drugs and perfumes.
21.Give the uses of ethyl alcohol?
It is used as a solvent for paints drugs oils perfumes dyes varnishes,medicines and gums.It is used for the preservations of biological specimens and as an antifreeze for automobile radiators.It is useed as a petrol substitute and as a fuel in spirit lamps and stoves.
22.What are structures of carbolic acid and picric acid?
23.What ar three important dihydro benzenes?Give their IUPAC names and old names?
24.How chlorobenzene is converted into phenol?
25.How benzene sulphonic acid can be converted into phenol?
26.Give physical properties of phenol?
It is colorless hygroscopic crystaline solid melts at 4ᵒC adn boils at 182ᵒC.It is partially miscible with water and readily soluble in alcohol.It is poisonous substance and produces  painful blisters in contact with the skin.
27.Why phenol is acidic but alcohol is not?How do you compare H2O with them?
28.How the resonance structures of phenoxide ion make phenol acidic?
When phenol gives the protons phenoxide ion which is produced develops the five resonance structures and attains the stability.It favours the reaction to the forward direction adn makes the phenol to release the proton.
29.How phenol can be converted into benzene?
30.What is the reaction of bromine water with phenol?
When bromine water reacts with phenol tribromophenol is produced which settles down in the form of white ppt.So phenol can be distinguished from other substances b this reaction.
31.Conc.HNO3 reacts with phenol to give picric acid?How?
          – OH group is o-,p-directing with activation.
32.What important polymer is produced by the reaction of phenol with methanal?
When phenol is reacted  with  methanal solution ortho and para positions of phenols are occupied by – CH2– OH group.These  compounds condense with each other to give a polymer called bakelite.The joining of molecule eliminates H2O.
33.Give the uses of phenol?
Phenol is used to produce bakelite drugs phenolphthalene and explosives .It is used as a wood preserative in gervicides and in antiseptic.
34.How do you compare phenol and ethyl alcohol?
NaOH and FeCI3 react with phenol but not with  alcohol.Phenol does not react with carboxylic  acids and halogen acids but alcohols do.Phenols react with diazonium salts to give dyes but alcohols do not  give this reaction.
35.What is williamson’s synthesis of ethers?
36.How silver oxide reacts with alkyl halides to give ethers?
37.How do acids react with ethers to give oxonium ions?
38.Give the mechanism of the reaction of halogen acids with ethers?
39.Give the uses of diethyl ether?
Ether is used as a general anaesthetic  and as  refrigerant.It can  act as a solvent for the extraction of organic compounds and can  dissolve  fats oils and resins.IT si a substitute of petrol by mixing with  alcohol.It is used as a perfumery adn the manufacture of smokeless gun powder.
40.What are mixed ethers?Give examples?
Those ethers in which  two alkyl or aryl groups attached with oxygen  atom are not alike are called  mixed ehters.
CH3 – o –C2H5………………… Ethyl methyl ether .
C2H5 – O-C3H7…………………. Ethyl propyl ether.
CH3 – O – C6H5…………………. Methyl phenyl ether.
41.Ethers belong to an inert class of organic compounds.Discuss?
Ethers adn alcohols are alkyl derivatives of water.Ethers have least hydrogen bonding and little tendency break C- O bond as compared to alcohols and water  which have  O-H  bonds in them.Actually alkyl groups are dominants  and they show their properties.
42.Ethers are less reactive than alcohois.Justify?
Ethers and alcohols are alkyl derivatives of water.Ethers have least hydrogen  bonding and little tendency break C-O bond as compared to alcohol and water which  have O – H  bonds in them.

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