Samacheer Kalvi 10th Science Solutions Chapter 11 Pdf
Tamilnadu Board Samacheer Kalvi 10th Science Solutions Chapter 11: Tamilnadu State Board Solution Class 10 Science Chapter 11 – Carbon and its Compounds.
Samacheer Kalvi 10th Science Solutions Chapter 11: Overview
Board |
Samacheer Kalvi |
Class |
10 |
Subject |
Science |
Chapter |
11 |
Chapter Name |
Carbon and its Compounds |
Samacheer Kalvi 10th Science Solutions Chapter 11
I.) Choose the best answer.
1.) The molecular formula of an open chain organic compound is C3H6. The class of the compound is
a) alkane
b) alkene
c) alkyne
d) alcohol
Ans:b) alkene
Because, it has 3 carbon atoms and 6 hydrogen atoms in its molecular formula.
2.) The IUPAC name of an organic compound is 3-Methyl butan-1-ol. What type compound it is?
a) Aldehyde
b) Carboxylic acid
c) Ketone
d) Alcohol
Ans:d) Alcohol
Because, the secondary suffix 1-ol represents the presence of –OH group.
3) The secondary suffix used in IUPAC nomenclature of an aldehyde is ____
a) –ol
b) –oic acid
c) – al
d) – one
Ans:c) – al
4.) Which of the following pairs can be the successive members of a homologous series?
a) C3H8 and C4H10
b) C2H2 and C2H4
c) CH4 and C3H6
d) C2H5OH and C4H8OH
Ans:a) C3H8 and C4H10
Because, these are successive alkanes i.e. propane and butane.
5.) C2H5OH + 3O2 → 2CO2 + 3H2O is a
a) Reduction of ethanol
b) Combustion of ethanol
c) Oxidation of ethanoic acid
d) Oxidation of ethanal
Ans:b) Combustion of ethanol
Because, ethanol is highly inflammable and burns with oxygen by liberating carbon dioxide and water.
6.) Rectified spirit is an aqueous solution which contains about _______ of ethanol
a) 95.5 %
b) 75.5 %
c) 55.5 %
d) 45.5 %
Ans:a) 95.5 %
7.) Which of the following are used as anaesthetics?
a) Carboxylic acids
b) Ethers
c) Esters
d) Aldehydes
Ans:b) Ethers
Because, ethers are used as anaesthetics and painkillers also.
8.) TFM in soaps represents ___________ content in soap
a) mineral
b) vitamin
c) fatty acid
d) carbohydrate
Ans:c) fatty acid
Because, TFM in soaps represents the fatty acid content in it.
9.) Which of the following statements is wrong about detergents?
a) It is a sodium salt of long chain fatty acids
b) It is sodium salts of sulphonic acids
c) The ionic part in a detergent is –SO3 –Na+
d) It is effective even in hard water.
Ans:a) It is a sodium salt of long chain fatty acids
Because, detergents are sodium salts of sulphonic acids.
II.) Fill in the blanks
1.) An atom or a group of atoms which is responsible for chemical characteristics of an organic compound is called ____________.
Ans: An atom or a group of atoms which is responsible for chemical characteristics of an organic compound is calledfunctional group.
2.) The general molecular formula of alkynes is _____________
Ans: The general molecular formula of alkynes is CnH2n-2.
3.) In IUPAC name, the carbon skeleton of a compound is represented by _________ (root word / prefix / suffix)
Ans: In IUPAC name, the carbon skeleton of a compound is represented by root word.
4.) (Saturated / Unsaturated) ___________ Compounds decolourize bromine water.
Ans: Unsaturated compounds decolourize bromine water.
5.) Dehydration of ethanol by conc. Sulphuric acid forms _______ (ethene/ ethane)
Ans: Dehydration of ethanol by conc. Sulphuric acid formsethene.
6.) 100 % pure ethanol is called ____________
Ans: 100 % pure ethanol is calledabsolute alcohol.
7.) Ethanoic acid turns _______ litmus to _________
Ans: Ethanoic acid turnsblue litmus to red.
8.) The alkaline hydrolysis of fatty acids is termed as _____________
Ans: The alkaline hydrolysis of fatty acids is termed as saponification.
9.) Biodegradable detergents are made of _________(branched / straight) chain hydrocarbons
Ans: Biodegradable detergents are made ofstraight chain hydrocarbons.
III. Match the following
Ans:
1) Functional group –OH:Alcohol
2) Heterocyclic: Furan
3) Unsaturated: Ethene
4) Soap:Potassium stearate
5) Carbocyclic: Benzene
IV.) Assertion and Reason: Answer the following questions using the data given below:
i) A and R are correct, R explains the A.
ii) A is correct, R is wrong.
iii) A is wrong, R is correct.
iv) A and R are correct, R doesn’t explains A.
1.) Assertion: Detergents are more effective cleansing agents than soaps in hard water.
Reason: Calcium and magnesium salts of detergents are water soluble.
Ans:A is correct, R is wrong.
2.) Assertion: Alkanes are saturated hydrocarbons.
Reason: Hydrocarbons consist of covalent bonds.
Ans:A and R are correct, R doesn’t explains A.
V.) Short answer questions
1.) Name the simplest ketone and give its structural formula.
Ans:
- The simplest ketone is acetone, containing three carbon atoms with molecular formula as C3H6
- The structural formula of acetone is as given below.
2) Classify the following compounds based on the pattern of carbon chain and give their structural formula:
1) Propane: Propane is a open chain compound as it contains open chain of three carbon atoms.
The structural formula of propane is CH3– CH2 – CH3
2) Benzene: Benzene is the carbocyclic compound containing cycle of six carbon atoms and its structural formula is as given below.
iii) Cyclobutane: Cyclobutane is also the carbocyclic compound containing the cycle of four carbon atoms and its structural formula is as below.
iv) Furan: Furan is the heterocyclic compound as it contains the cycle of four carbon atoms and one oxygen atom also and its structural formula is as given below.
3) How is ethanoic acid prepared from ethanol? Give the chemical equation.
Ans:
Ethanol in the presence of alkaline potassium permanganate of acidified potassium dichromate undergoes oxidation and ethanoic acid is formed. The chemical equation of it is as given below.
CH3CH2OH → CH3COOH + H2O, in the presence of KMnO4, OH–, 2[O]
Ethanol Ethanoic acid
4) How do detergents cause water pollution? Suggest remedial measures to prevent this pollution?
Ans:
Some of the detergents which are the non-biodegradable detergents, are having a branched hydrocarbon chain and these are not completely biodegradable by the micro-organisms present in water. And hence they cause water pollution. And they are also relatively more expensive than soaps.
To prevent the water pollution we have to use the biodegradable detergents which are in the form of straight hydrocarbon chains, and which can be easily biodegradable by the bacteria present in the water and hence there is no water pollution.
5) Differentiate soaps and detergents.
Ans:
Soaps:
- Soaps are the sodium salts of long chain fatty acids.
- They contains the ionic part as –COO–Na+
- Soaps are prepared from the animal fats or vegetable oils.
- Their effectiveness is reduced when they are used in the hard water.
- They forms scum in hard water.
- Soaps are having poor foaming capacity.
- And soaps are biodegradable.
Detergents:
- Detergents are sodium salt of sulphonic acid.
- They contains the ionic part as –SO–3Na+
- Detergents are produced from hydrocarbons which are obtained from the crude oil.
- Detergents are effective in hard water.
- They does not forms the scum in hard water.
- They are having rich foaming capacity.
- Most of the detergents arenon-biodegradable.
VI.) Long answer questions
1) What is called homologous series? Give any three of its characteristics?
Ans:
Homologous series:
It is the group or the class of organic compounds having the same general formula and similar chemical properties in which the successive members differ by a –CH2 group.
For example:
Methane: CH4
Ethane: CH3CH3
Propane: CH3CH2CH3
Butane: CH3(CH2)2CH3
Pentane: CH3(CH2)3CH3
Above is the homologous series as each successive member has one methylene group more than the precedent member of the series.
Characteristics of homologous series:
- Each member of this series differs from the preceding or succeeding member by one methylene group that means by a molecular mass of 14 amu.
- The functional group and the elements are same in all homologous series.
- The general molecular formula for homologous series e.g Alkanes is CnH2n+2.
- The homologous series elements are having similar chemical properties.
- And all these homologous series members are prepared by a common method.
2) Arrive at, systematically, the IUPAC name of the compound: CH3–CH2–CH2–OH.
Ans:
The given compound 3 2 1
CH3–CH2–CH2–OH
Step 1: Here, the parent chain consist of 3 carbon atoms, so the root word is “Prop”.
Step 2: There are single bonds between the carbon atoms of the chain and hence the primary suffix is “ane”.
Step 3: As the compound contains –OH group it is an alcohol and the numbering is given from that carbon which is closest to –OH group.
Step 4: As the locant number of –OH group is 1 and hence the secondary suffix is “1-ol”.
Thus, the name of the compound is Propan-1-ol
3) How is ethanol manufactured from sugarcane?
Ans:
Manufacture of ethanol:
The byproduct obtained during the manufacture of sugar from sugarcane is the molasses which is fermented to obtain ethanol.
It is the dark coloured syrupy liquid and contains 30% of sucrose which cannot be separated by crystallization.
The steps involved in manufacturing the ethanol are explained as follows.
1) Dilution of molasses:
Initially molasses are diluted by using water to reduce the concentration of sugar up to 8-19%.
2) Addition of nitrogen source:
Molasses already contains the enough nitrogenous matter which acts as a food for yeast during fermentation process. It nitrogen content is less then ammonium sulphate or phosphate is added.
3) Addition of yeast:
The solution is taken from step 2 above explained and collected in large fermentation tanks by adding yeast in it. And this mixture is kept at about 303K for some days. And this period the enzymes invertase and zymase present in yeast converts sucrose into ethanol.
Invertase
C12H22O11 + H2O → C6H12O6 + C6H12O6
Sugar Glucose Fructose
Zymase
C6H12O6 → 2C2H5OH + 2CO2
Glucose or Ethanol
Fructose
4) Distillation of wash:
The fermented liquid is fractional distillated and pure alcohol is obtained called as absolute alcohol.
4) Give the balanced chemical equation of the following reactions:
Ans:
1) Neutralization of NaOH with ethanoic acid:
Ethanoic acid reacts with sodium hydroxide and forms sodium ethanoate and water.
CH3COOH + NaOH → CH3COONa + H2O
Ethanoic acid sodium ethanoate
2) Evolution of carbon dioxide by the action of ethanoic acid with NaHCO3:
When ethanoic acid reacts with weak base like sodium bicarbonate liberates CO2.
CH3COOH + NaHCO3 → CH3COONa + CO2 ↑ + H2O
Ethanoic acid sodium ethanoate
3) Oxidation of ethanol by acidified potassium dichromate:
Ethanol is oxidized to ethanoic acid in the presence of acidified K2Cr2O7.
In this reaction the orange coloured potassium dichromate changes to green. And hence this reaction is also used for identifying the alcohols.
CH3CH2OH → CH3COOH + H2O
Ethanol Ethanoic acid
4) Combustion of ethanol:
Ethanol is highly inflammable liquid as it burns with oxygen and forms carbon dioxide and water.
CH3CH2OH + 3O2 → 2CO2 + 3H2O
Ethanol Carbon dioxide
5) Explain the mechanism of cleansing action of soap.
Ans:
Mechanism of cleaning action of soap:
- A soap molecule has two chemically different parts which interacts with water differently.
- It has one polar end that is the short head with a carboxylate group –COONa and second is the non-polar end with long tail made up of the hydrocarbon chain.
- The polar end is water loving i.e. hydrophilic in nature and it is attracted towards the water.
- While the non-polar end is hydrophobic i.e. water hating in nature and hence it is attracted towards the dirt or oil present on the cloth and not attracted towards the water.
- Thus, this hydrophobic part traps the dirt and hydrophilic parts makes entire molecule soluble in water.
- When the soap or detergent is dissolved in water, the molecules join together like a cluster called as micelles. As they are having long hydrocarbon chains get attached to the oil and dirt. Thus dirt is surrounded by non-polar end of the soap molecule.
- The charged carboxylate end of the soap molecules makes the micelles soluble in water and in this way dirt is washed away with the soap.
VII.) HOT questions
1) The molecular formula of an alcohol is C4H10O. The locant number of its –OH group is 2.
i) Draw its structural formula:
ii) Give its IUPAC name:
Its IUPAC name is Butan-2-ol.
iii) Is it saturated or unsaturated?
As all bonds in Butan-2-ol are single bonds hence it is saturated compound.
2) An organic compound ‘A’ is widely used as a preservative and has the molecular formula C2H4O2. This compound reacts with ethanol to form a sweet smelling compound ‘B’.
Ans:
i) Identify the compound ‘A’:
Here, the compound A is acetic acid CH3COOH which is widely used as preservative.
ii) Write the chemical equation for its reaction with ethanol to form compound ‘B’:
Acetic acid reacts with ethanol and forms fruity smell ester called as ethyl acetate.
CH3COOH + C2H5OH → CH3COOC2H5 + H2O
Acetic acid Ethanol Ethyl acetate
iii) Name the process:
The process of formation of ester from alcohol is called as esterification.
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