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Carbon (C) |
Unique element with atomic Number 6 and electronic
configuration 2, 4 and valency of 4. Around 30 million plus compounds made of
Carbon |
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Allotropes of Carbon |
Pure carbon exists in different physical forms such as
Diamond, Graphite, Buckminster Fullerene, Graphene, carbon Nanotubes etc |
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Versatile nature of carbon |
Due to Catenation, Tetravalency, Small Size |
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Hydrocarbons |
Compounds that of Carbon and Hydrogen in a fixed
proportion. They include Alkanes (CnH2n+2), Alkenes (CnH2n) & Alkynes
(CnH2n-2) |
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Functional groups |
Atom, Molecule or a Bond that gives different physical
& chemical properties to a Hydrocarbon Chain |
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Examples of Functional groups |
Alcohols (-OH), Aldehydes (-CHO), Ketone (-C=O),
Carboxylic acids (-COOH), Halogens (-Cl, -Br, -I) |
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Chemical Properties of Carbon and its compounds |
Combustion: e.g. CH4 + O2 -> CO2 + H2O Oxidation: e.g. C2H5OH + KMnO4 -> CH3COOH Addition: e.g. CH2=CH2 + H2 -> C2H6 Substitution: e.g. CH4 + Cl -> CH3Cl |
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Ethanol (C2H5OH) |
M.P: -117C, B.P: 77C, Reacts with Sodium to form Sodium
ethoxide, Reacts with Sulphuric acid to form Ethene |
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Ethanoic Acid (CH3COOH) |
M.P: 17C, B.P: 117C, Reacts with ethanol to form
esters, Reacts with Sodium Hydroxide to form Sodium Acetate |
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Soaps |
Soaps are Sodium or Potassium salts of long chain fatty
acids, Clean by forming Micelles, Do not work in Hard water |
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Detergents |
Ammonium or Sulphonate salts of long chain fatty acids.
Work both in hard and soft water |
Or
Draw electron dot structure of H2, O2, N2.
Ans: The bond formed by mutual sharing of electrons between two atoms in such a way that both the atoms become stable.
The pair of shared electron is represented by putting a single line (__) between two atoms.
Formation of Hydrogen Bond (H2)
Hydrogen has atomic number of 1, An atom of H share one electron with other so both atoms complete their outer shell.
H . + . H ----> H : H ---> H _ H
Formation of Oxygen Bond (O2)
Oxygen has atomic number of 8. An atom of O share two electrons with other, so both atoms complete their outer shell.
. . . . . . . .
O : + O : -----> O : : O ---> O=O
. . . . . . . .
Formation of Nitrogen Bond (N3)
Nitrogen has atomic number of 7. An atom of N share three electrons with other, So both atoms complete their outer shell.
: N : + : N : -----> N . . . N ----> N≡N
Q. What is allotropy? Name the different allotropic forms of carbon?
Ans: When an element exists in different physical forms but having similar chemical properties. The phenomenon is called allotropy and the various forms are called allptropic forms.
Carbon exists in varous allotropic forms such as Diamond, Graphite, Fullerene.
Q. Discuss the versatile nature of carbon?
Or
Why carbon forms large number of compounds we see around us?
Ans: Carbon forms covalent bond. It forms large number of compounds due to following reasons;
A. Catenation: It is the property of carbon atom due to which large number of carbon atoms link to form long chains.
- c - c - c - c - c - c -
B. Tetra Valency: Carbon shows tetravalency. Carbon needs four electrons to become stable. It forms bonds with other carbon atoms and other elements.
Q. Distinguish between saturated and unsaturated
hydrocarbons.
Ans:
|
Saturated Hydrocarbons |
Unsaturated
Hydrocarbons |
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They have single
covalent bond |
They have
double or triple covalent bond |
|
The general formula
is CnH2n+2 |
The general
formula is CnH2n or CnH2n-2 |
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They are less
reactive |
They are more
reactive |
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They include
Alkanes |
They include
Alkenes and Alkynes |
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They burn with
clean flame |
They burn
with sooty flame |
Q. What is Homologus series? State the Characteristics of homologus series?
Ans: Homologus series is a series of compounds that has same structural formula, Properties and functional group. The homologus series differ only in number of carbon atoms.
E.g, Homologus series of Aldehydes include
H - CHO Methanal
CH3- CHO Ethanal
C2H5 - CHO Propanal
Characteristics of homologus series;
1. Compounds of a series only differ in carbon unit
2. They has a general formula.
3. They have same functional group.
4. They have similar chemical properties.
Q. Describe the important chemical properties of Carbon compounds?
Ans: Some of important chemical properties of carbon are :
1. Combustion: The carbon and its compounds react with oxygen to produce carbon dioxide, water and large amount of heat and light.
Examples:
CH4 + 2 O2 ------> CO2 + 2 H2O
Methane oxygen Water
2. Addition Reaction: The Unsaturated hydrocarbons add hydrogen to form saturated hydrocarbons.
Example
CH2 = CH2 + H2 Ni > CH3-CH3
Ethene Ethane
3. Oxidation: Carbon compounds also undergo oxidation reaction
Example:
C2H5 OH KMnO4 > CH3 COOH
4. Substitution reaction: When chlorine is added to hydrocarbons. It replaces hydrogen atoms. The reaction is substitution reaction.
Example:
CH4 + Cl2 _____> CH3Cl + HCL
Q. Explain the Physical and Chemical properties of Ethanol?
Ans: Ethanol is commonly called as Alcohol. Ethanol is liquid at room temperature. It is a good solvent.
Its melting point is - 117 °C and boiling point is 77 °C.
Its formula is C2H5OH.
Chemical Properties:
1. Reaction with Sodium:
Ethanol reacts with Sodium to form Sodium ethoxide.
C2H5OH + Na ______> C2H5O-Na + H2
2. Reaction with sulphuric acid:
Ethanol is heated with Concentrated Sulphuric acid to form Ethene.
C2H5OH + H2SO4 ______> CH2 = CH2 + H2O
Sulphuric acid acts as dehydrating agent.
Q. Explain the physical and chemical properties of Ethanoic acid?
Ans: Ethanoic acid is commonly called as Acetic acid. Ethanoic acid is liquid at room temperature.
Its melting point is 17 °C, hence it freezes in winters.
Ethanoic acid is a type of carboxylic acid and is a weak acid.
Its formula is CH3COOH.
Chemical Properties:
1. Esterification reaction:
When Ethanoic acid reacts with Ethanol, it forms Esters.
CH3COOH + C2H5OH _> CH3-C=O-C2H5
Esters are sweet smelling substances.
2. Reaction with Base:
CH3COOH +NaOH ___> CH3COO-Na + H2O
Q. Draw the structure of following compounds;
1. 1-Butene
2. 2- Iodo Propane
3. 2- Propanol
4. Butanoic acid
5. 3- Pentanone
Ans:
.png "Q. Draw the structure of following compounds; 1. 1-Butene 2. 2- Iodo Propane 3. 2- Propanol 4. Butanoic acid 5. 3- Pentanone")
Q. Draw the structure of
i. Bromo pentane
ii. Hexanal
iii. Propene
iv. 2,3- Dimethyl Butane v. 2 Propanol
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Q. Give
the molecular formula of one homologue of each of the following:
i. C3H6
ii. C2H6
iii.
C2H2
b. What
is the difference in molecular mass of any two adjacent homologues.
c. By
how many carbon atoms and hydrogen atoms do any two adjacent homologues differ?
Ans: (i) The molecular formula of a homologue of C3H6 is C4H8. They are Alkenes.
(ii) The molecular formula of a homologue of C2H6 is C3H8. They are Alkanes.
(iii) The molecular formula of a homologue of C2H2 is C3H4. They are Alkynes.
B. The difference in molecular mass of two adjacent homologues is that of 1 Carbon and 2 Hydrogen.
We know Molecular mass of Carbon is 12 U and Hydrogen is 1 U.
i.e., 12 + 1 x 2 = 14 U
C. They differ in 1 carbon and 2 hydrogen atoms.
Q. What
are Isomers? Give an example of Isomers.
Ans: The
organic compounds having the same molecular formula but different structures
are known as isomers. E.g. n Butane and Iso Butane.
Q. Write
the structural formula of C7H16.
Ans: C7H16
is Heptane. Its structural formula is:
Q. How
many Isomers of the following hydrocarbons are possible?
i. C3H8 ii. C4H10 iii. C5H12 iv. C6H14
Ans: When
the number of Carbon atoms increases, the number of Isomers also increase.
i. C3H8: It
has no Isomers.
ii. C4H10:
It has 2 isomers.
iii. C5H12:
It is 3 Isomers.
iv. C6H14: It is 5 isomers.
Ans:
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Q. Draw the electron dot structure of Cyclopentane.
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Q. Explain the following reactions with examples:
i. Oxidation reactions ii. Substitution reactions
Ans: The carbon and its compounds undergo Oxidation and Substitution.
A. Oxidation Reactions: Carbon and its compounds undergo oxidation reactions. In these reactions, compound of carbon react with oxidizing agents such as KMnO4 or K2Cr2O7.
Example:
C2H5OH + K2Cr2O7 −−−−−−−→ CH3COOH
B. Substitution Reaction: Carbon and its compounds undergo substitution reactions. In these reactions, Alkanes react with Halogens such as chlorine, bromine or Iodine which replaces Hydrogen atom from the alkane.
Example: CH4 + Cl -----> CH3Cl
Q. Write the IUPAC names of following compounds
Ans: i. Propanal
ii. 2-Butene
iii. 2 Bromo Propane
iv. 4 Pentanone
v. Propanoic Acid
Q. What is an Esterification Reaction? Describe an activity to show esterification.
Ans: Esterification is a chemical reaction that occurs when an alcohol and a carboxylic acid react in the presence of an acid catalyst. The reaction produces a compound with a sweet smell called an esters.
Activity to show Esterification:
i. Add 1 ml of pure ethanol to a test tube
ii. Add 1 ml of ethanoic acid to the ethanol
iii. Add 2 to 3 drops of concentrated sulfuric acid to the mixture
iv. It will produce Esters
Example:
Ans: The electron dot structure of carbon dioxide (CO2) is;
Ans: The atomic number of sulphur is 16. It exits in nature as S8. Its electrom dot structure is:
Ans: There are three structural isomers of Pentane. They are n-Pentane, Neo-Pentane, Iso- Pentane.
Q. What will be the formula and electron dot structure of cyclopentane?
Ans: The formula of Cyclo-pentane is C5H10. Its electron dot structure is;
Ans: Benzene is an Aromatic compound with the formula C6H6. Its Dot structure is given below;
a. Ethanoic Acid
b. Bromopentane
c. Butanone
Ans:
Q. What are oxidizing agents?
Ans: Oxidizing agents are the chemicals which give oxygen in an oxidation reaction.
E.g Potassium Permagnate (KMnO4).
Q. Why the conversion of ethanol to ethanoic acid is an oxidation reaction?
Ans: The conversion of ethanol is an oxidation reaction because the ethanol reacts with oxygen to form ethanoic acid.
Q. A mixture of oxygen and ethyne is burnt for welding. Can you tell why mixture of ethyne and air is not used?
Ans: Oxygen and ethyne produce clean flame with high temperature. The mixture of Ethyne and air is not used in welding because the air produces sooty flame and doesn't burn properly.
Q. How will you distinguish experimentally between alcohol and carboxylic acid?
Ans: Carboxylic acid turns blue litmus red. The Alcohol on other hand do not turn blue litmus red.
When Carboxylic acid is reacted with sodium bicarbonate. The solution becomes milky.
Q. Explain the mechanism of cleaning action of soaps?
Ans: Soaps are sodium or potassium salts of fatty acids. A molecule of soap contains two parts;
i. Hydrophobic long chain hydrocarbon
ii. Hydrophilic Polar group.
Ans: Detergents are ammonium or sulphonate salts of long chain carboxylic acids. They form lather with both hard water and soft water. So it is not possible to check if water is hard by using detergent.
Q. Explain formation of scum when hard water is treated with soap?
Ans: Hard water contains high mineral content. The minerals react with soap molecules to form salts.
These salts form scum over surface of water.
Q. Explain the nature of covalent bond using bond formation of CH3Cl?
Ans:
The carbon has 4 electrons in outer shell. It shares its electrons with 3 hydrogen atoms and 1 chlorine atom to complete its octet.
Ans: Ethanol is basic having pleasant smell where as ethanoic acid is acidic having vinegar smell.
Ethanol has no action on litmus paper, Ethanoic acid turns blue litmus red.
Ethanol doesnt react with sodium bicarbonate, Ethanoic acid reacts with sodium bicarbonate.
Q. Why are carbon and its compounds used as fuels for most applications?
Ans: The carbon and its compounds burn with clean flame. They have high calorific value and are easily available.
Q. What changes will you observe if you test soap with litmus paper?
Ans: Soaps are basic in nature. They turn red litmus blue.
Q. What is hydrogenation? What are its industrial applications?
Ans: Hydrogenation means addition of hydrogen to a chemical compound.
Hydrogenation converts unsaturated hydrocarbons into saturated hydrocarbons.
Example;
CH2 = CH2 + H2 ______> CH3 - CH3
In Industries, it is used to convert oils into ghee.
Q. Give a test that can be used to differentiate chemically between butter and cooking oil.
Ans: Cooking oil is liquid at room temperature while as butter is solid.
Test to differentiate between oil and butter:
Add Mercury chloride HgCl2 to Alcohol.
Add iodine solution to it. The voilet colour is formed.
If we add cooking oil, the voilet colour fades away. If we add butter to it, the colour remains same.
Q. Calculate the difference in the formulae and molecular masses of:
a. CH3OH and C2H5OH
Ans: There is difference of 1 carbon and 2 Hydrogen in the formulae of CH3OH and C2H5OH.
There is also difference of 14 U in the molecular mass of CH3OH and C2H5OH.
b. C2H5OH and C3H7OH
Ans: There is difference of 1 carbon and 2 Hydrogen in the formulae of C2H5OH and C3H7OH.
There is also difference of 14 U in the molecular mass of C2H5OH and C3H7OH.
c. C3H7OH and C4H9OH
Ans: There is difference of 1 carbon and 2 Hydrogen in the formulae of C3H7OH and C4H9OH.
There is also difference of 14 U in the molecular mass of C3H7OH and C4H9OH.
Q. How many structural isomers are possible for Bromo-Pentane?
Ans: There are 8 structural isomers possible for Bromo-Pentane.
Q. How would you name the following compounds?
i. Bromo Ethane
ii. Methanal
iii. Hexyne
Q. If you drop small piece of sodium into Ethanol, Which gas will evolve from it?
Ans: When small piece of sodium is dropped into ethanol, the hydrogen gas will evolve.
The reaction can be written as:
Q. Draw the electron dot structure of
a. Ethanoic acid
b. H2S
c. Propanone
d. F2
Ans:
Q. Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?
Ans: The soap molecules are Sodium or Potassium salts of long chain fatty acids with two ends i.e. Hydrophobic end and hydrophilic end.
Inside the water, the hydrophobic ends align away from water and attach to dirt, oil molecules form micelles.
The micelles will not form in solvents like ethanol as the soap molecule will get dissolved and disintegrated in ethanol.
Q. Which of the following hydrocarbons undergo addition reactions: C2H6, CH3, C3H6, C2H2 and CH4?
Ans: Since only unsaturated hydrocarbons i.e. Alkenes and alkynes undergo addition reaction, therefore C3H6, C2H2 as well as CH3 will undergo addition reactions.
Note: Saturated Hydrocarbons undergo Substitution reactions.
Q. Discuss four properties of ionic compounds.
Ans: The four properties of Ionic compounds are:
i. They have high melting point
ii. They have high boiling point
iii. They conduct electricity
iv. They are brittle
Ans: The covalent compounds have low melting and boiling points because of the weak intermolecular bonds (Covalent bonds) present between its atoms.
Objective Type Questions:
Q. Name the functional group which always occurs at the middle of carbon chain.
Ans: The Ketone is always present at the middle of carbon chain.
Q. Why does ethyne burn with a sooty flame?
Ans: When ethyne is burned in air, it does not get completely oxidised, thereby producing a sooty flame.
Q. What is the common name of Methanol
Ans: Spirit or Methyl Alcohol
Q. Name the product formed when hydrogen is added to ethene.
Ans: When Hydrogen is added to Ethene, Ethane is formed.
Q. Name a covalent molecule having a double bond between its atoms.
Ans: Oxygen (O2)
Q. What is the common name of Propanone?
Ans: Acetone.
Q. Name the gas evolved when ethanoic acid is added to sodium carbonate
Ans: When ethanoic acid is added to Sodium carbonate, Carbon dioxide is formed.
Ans: Cn H 2n+1 COOH forms CH3COOH. Its name is ethanoic acid. It is also called as acetic acid.
Q. From an alkane containing two carbon atoms, one hydrogen atom is replaced by a hydroxyl group to form a new compound. Name the newly formed compound and write its molecular formula.
Ans: An Alkane containing two carbon atoms is Ethane (C2H6).
When one Hydrogen atom of Ethane is replaced by hydoxyl group, it forms C2H5OH.
C2H5OH is also called as ethanol.
Ans: An Alkane with 3 carbon atoms is Propane (C3H8).
If one hydrogen atom is replaced by chlorine, it forms ChloroPropane.
The molecular formula of ChloroPropane is C3H7Cl.
Q. Homologus series is a family of organic compounds having same functional group. Give the formulae of first three homologues of carboxylic acids.
Ans: The first three carboxylic acids are;
1. Methanoic acid (HCOOH),
2. Ethanoic acid (CH3COOH),
3. Propanoic acid (C2H5COOH)
Q. Name the part of soap molecule that is hydrophilic.
Ans: The ionic oart of soap molecule i.e C=O_O-Na is hydrophilloc in nature.
Q. Ethane, with the molecular formula C2H6 has;
a.) 6 covalent bonds b.) 7 covalent bonds
c.) 8 covalent bonds d.) 9 covalent bonds
Ans:-- 7 covalent bonds.
Q. Butanone is a four- carbon compound with the functional group;
a.) carboxylic acid b.) aldehyde
c.) ketone d.) alcohol
Ans:-- ketone.
Q. While cooking, if the bottom of vessel is getting black on the outside, it means that:
a. The food is not cooker properly
b. The fuel is not burned properly
c. The fuel is wet
d. The fuel is burning completely
Ans: b. The fuel is not burned properly
Q. which of the following types of medicines are used for treating in digestions?
a.) Antibiotic b.) Analgesic
c.) Antacid d.) Antiseptic
Ans:--- Antacid.
Q. Carboxylic acid group is present in one of the following;
a.) Propanone b.) Acetaldehyde
c.) Ethanoic acid d.) Hydrochloric acid
Ans:-- Ethanoic acid.
Q. Vinegar is;
a.) 25% acetic acid b.) 6- 8% acetic acid
c.) pure acetic acid d.) 50% acetic acid
Ans:-- 6- 8% acetic acid
Q. Aldehyde group is present in one of the following;
a.) Propanone b.) Acetaldehyde
c.) Ethanoic acid d.) Hydrochloric acid
Ans:-- Acetaldehyde.
8. Ethane with molecular formula C2H6 has:
a) 6 Covalent bonds b) 8 Covalent bonds c) 7 Covalent bonds d) 9 Covalent bonds
Ans: c) 7 Covalent bonds
Q. Which among the following represents the functional group of aldehydes
a. -COOH b. CHO c. -C=O d. C=C
Ans: c. -C=O
Q. Butanone is a four carbon compound with the functional group:
a. -COOH b. -CHO c. -C=O d. -C-Br
Ans: b. -CHO
Q. Which of the following has 10 covalent bonds
a. Ethane b. Propane c. Butane d. Pentane
Ans: b. Propane
Q. Assertion (A): The two characteristic features seen in
carbon, that is tetravalency and catenation.
Reason (R) : Carbon atom has four valence electrons in its
outermost shell which makes it possible to form large number of compounds.
Ans: (A) A and R are true and R is the correct explanation
of A.
Q. Draw electron dot structure of Ammonia molecule?
Ans:
Ans:
