Solutions of Carbon And Its Compounds (Page No - 266) - Chemistry Lakhmir Singh, Class 10 | Extra Documents, Videos & Tests for Class 10 PDF Download

Question 66:
A neutral organic compound X of molecular formula C₂H₆O on oxidation with acidified potassium dichromate gives an acidic compound Y. Compound X reacts with Y on warming in the presence of cone. H₂S0₄ to give a sweet smelling substance Z. What are X, Y and Z ?
 Solution :
X is ethanol
Y is ethanoic acid
Z is ethyl ethanoate
Ethanol reacts with ethanoic acid to form ethyl ethanoate ester.

Question 67:
Consider the following organic compounds :
 HCHO, C₂H₅OH, C₂H₆, CH₃COOH, C₂H₅C1
 Choose two compounds which can react in the presence of cone. H₂S0₄ to form an ester. Give the name and formula of the ester formed.
 Solution :
C₂H₅OH and CH₃COOH react in the presence of conc. H₂SO₄ to form an ester. Ethyl ethanoate, CH₃COOC₂H₅ is formed in the reaction.

Question 68:
A neutral organic compound is warmed with some ethanoic acid and a little of cone. H₂S0₄. Vapours having sweet smell (fruity smell) are evolved. What type of functional group is present in this organic compound ? The structural formula of an ester is :
 Solution :
Alcohol group, -OH. Acids react with alcohols to form sweet smelling esters.

Question 69:
The structural formula of an ester is :

Write the formula of the acid and the alcohol from which it is formed.
Solution :

Question 70:
Consider the following organic compounds :
 CH3OH, C₂H₅OH, CH3COCH3, CH3COOH, C₂H₅COOH, C₄H₉COOC₂H₅, CH_4, C₂H₆, CH3CHO, HCHO Out of these compounds :
 (a) Which compound is most likely to be sweet-smelling ?
 (b) Which compound on treatment with cone. H₂S0₄ at 170°C forms an alkene ?
 (c) Which compound on repeated chlorination forms chloroform ?
 (d) Which compound is added to alcohol to denature it ?
 (e) Which compound is a constituent of vinegar ?
 (f) Which compound is used to sterilise wounds and syringes ?
 Solution :
(a) C₄H₉COOC₂H₅; Ester
(b) C₂H₅OH; Alcohol forms ethene, C₂H₄
(c) CH_4; Methane
(d) CH₃OH; Methanol
(e) CH₃COOH; Acetic acid
(f) C₂H₅OH; Ethanol

Question 71:
An organic acid X is a liquid, Which often freezes during winter time in cold countries, having the molecular formula C₂H₄0₂. On warming it with methanol in the presence of a few drops of concentrated sulphuric acid, a compound Y with a sweet smell is formed.
 (a) Identify X and Y. Also write their formulae showing the functional group present in them.
 (b) Write a chemical equation for the reaction involved.
 Solution :

Question 72:
An organic compound A having the molecular formula C₃H₈O is a liquid at room temperature. The organic liquid A reacts with sodium metal to evolve a gas which burns causing a little explosion. When the organic liquid A is heated with concentrated sulphuric acid at 170°C, it forms a compound B which decolourises bromine water. The compound B adds on one molecule of hydrogen in the presence of Ni as catalyst to form compound C which gives substitution reactions with chlorine.
 (a) What is compound A ?
 (b) What is compound B ?
 (c) What type of reaction occurs when A is converted into B ?
 (d) What is compound C ?
 (e) What type of reaction takes place when B is converted into C ?
 Solution :
(a) A is propanol, CH3-CH₂-CH₂OH
(b) B is propene, CH₃CH=CH₂
(c) Dehydration reaction
(d) C is propane, CH₃CH₂-CH₃
(e) Addition reaction