Carbon and Its Compounds
 |
| Allotropes of Carbon - Fulleren-Diamond-Graphite |
· Carbon is most abundant element in the universe. Nearly 20% of your body contains CARBON. Carbon is found in 4-major forms i.e. graphite, diamond, fullerene and newly discovered graphene in 2004.
·
Covalent bonds
are formed as a result of sharing of electrons. Example- H2, O2,
N2. Covalent compounds have low melting point and boiling point due
to small intermolecular forces.
·
H2
forms by sharing valence electrons (1 per atom of H) and produce single bond
between two hydrogen atoms.
·
O2 forms
by sharing valence electrons (2 per atom of O) and produce double bond between
two oxygen atoms.
·
N2
forms by sharing valence electrons (3 per atom of N) and produce triple bond
between two nitrogen atoms.
·
Methane, CH4
is simple carbon compounds and used as a fuel on large scale and also a major
component of CNG (Compressed Natural Gas). Methane formed due to sharing of 4
valence electrons of carbon with 4 hydrogen atoms.
Allotropes of Carbon
Carbon have
three allotropes i.e. Diamond, Graphite and fullerene.
1. Diamond:-
Diamond formed due to rigid three dimensional structures of carbon atoms
because each carbon atom bonded to another 4 carbon atoms. It is hardest
substance.
2. Graphite:-
Graphite
formed due to presence of hexagonal array layers above one another, and layers
of hexagonal arrays formed because each carbon atom bonded to another 3 carbon
atoms with 2 single and 1 double bond. It is smooth, slippery and very good
conductor of electricity.
3. Fullerenes:-
Fullerenes (C-60) are also an allotrope of carbon in which carbon atoms are
arranged in football like shape.
Versatile Nature of Carbon
Carbon shows versatile nature because
it has two characteristics features which are catenation and tetravalency. These
both feature gives large numbers of compounds.
1. Catenation:-
Catenation is the property of carbon atom to form bond with other carbon
atom to produce large molecule. Catenation produces large long chains, branched
chains and ring structures.
Compounds with single bonds are known as saturated compounds
while compounds with double or triple bonds are known as unsaturated compounds.
2. Tetravalency:-
Property of carbon atom to form 4 bonds with other atom of carbon or other
element is known as tetravalency, as carbon have four valence electrons.
Saturated and Unsaturated Carbon Compounds
1. Saturated Carbon Compounds:-
Carbon compounds containing single bond is called saturated Carbon Compounds.
Example- Ethane, C2H6
2. Unsaturated Carbon Compounds:-
Carbon
compounds containing double or triple bond is called unsaturated Carbon Compounds.
Example- Ethene, C2H4
Chains, Branches and Rings
Carbon is the element which forms chains,
branches and rings in its structures.
1. Chains:-
Carbons
have property to form chains, when one carbon atom attach to another carbon
atom like chains.
Example- Ethane(C2H6), Propane(C3H8),
Butane(C4H10), Pentane(C5H12),
Hexane(C6H14).
2. Branches:-
Carbon
forms branches when one and two carbon attach to carbon chain.
Example- Butane
3. Rings:-
Carbon
forms rings when all carbon atoms attach to one another means first carbon
chain atom attach to last carbon chain atom giving ring structure.
Example- Cyclohexane(C6H12)
Benzene(C6H6)
Alkane, Alkene and Alkynes
As we know hydrocarbons are the carbon
compounds containing carbon and hydrogen.
1. Alkane:-
Saturated hydrocarbons containing single bonds are known as alkanes.
Example- Ethane (C2H6)
2. Alkene:-
Unsaturated hydrocarbons containing double
bonds are known as alkenes.
Example- Ethene (C2H4)
3. Alkyne:-
Unsaturated hydrocarbons containing
triple bonds are known as alkynes.
Example- Ethyne (C2H2)
Chemistry of Bonding between Carbon and other atoms
Some elements (like
halogens, sulpher, oxygen, nitrogen) replace hydrogen from carbon compounds. These
elements which replace hydrogen are called as heteroatom.
This
heteroatom’s may be present in single or group form and gives specific property
to carbon compound and called as functional group. Function group attach to
carbon compound by replacing hydrogen atom.
List of Some Functional Group
Hetero-atom
|
Functional
Group
|
Formula of
Functional Group
|
Cl/Br/I
|
Halo-(Chloro/Bromo/Ido)
|
-Cl , -Br, -I
|
Oxygen
|
Alcohol
|
-OH
|
Aldehyde
|
-CHO
|
|
Ketone
|
-CO-
|
|
Carboxylic Acid
|
-COOH
|
Homologous Series
When same
functional group is present on carbon chains of varying length, such series of
carbon compounds is known as homologous series.
Example-
chemical properties of CH3OH, C2H5OH, C3H7OH
and C4H9OH are very similar.
Nomenclature of carbon compounds
To name any
carbon compound just follow below steps-
Step1- Calculate no. of
carbon atoms in carbon compound. For example
i.
If carbon
compound have 1 carbon atom then use prefix Meth
ii.
If carbon
compound have 2 carbon atom then use prefix use
prefix Eth
iii.
If carbon
compound have 3 carbon atom then use prefix Prop
iv.
If carbon
compound have 4 carbon atom then use prefix But
v.
If carbon
compound have 5 carbon atom then use prefix Pent
vi.
If carbon
compound have 6 carbon atom then use prefix Hex
vii.
If carbon
compound have 7 carbon atom then use prefix Hept
viii. If carbon compound have 8
carbon atom then use prefix Oct
ix.
If carbon
compound have 9 carbon atom then use prefix Non
x.
If carbon
compound have 10 carbon atom then use prefix Dec
xi.
If carbon
compound have 11 carbon atom then use prefix Undec
xii.
If carbon
compound have 12 carbon atom then use prefix Dodec
xiii. If carbon compound have 13
carbon atom then use prefix Tridec
xiv.
If carbon
compound have 14 carbon atom then use prefix Tetradec
xv.
If carbon
compound have 15 carbon atom then use prefix Pentadec
xvi.
If carbon
compound have 20 carbon atom then use prefix Eicos
xvii. If carbon compound have 30
carbon atom then use prefix Triacont
xviii. If carbon compound have 40
carbon atom then use prefix Tetracont
xix.
If carbon
compound have 50 carbon atom then use prefix Pentacont
Example- What is the name of
CH4,C2H6 ?
Number of carbon atom in CH4 is 1 so use Meth and it is alkane so use ane so its name is Methane
Similarly,
Number of carbon atom in C2H6 is 2 so use Eth and it is alkane so
use ane
so its name is Ethane.
Step2- if functional group is
present in carbon compound then it is indicated by adding a prefix or a suffix
for it as shown in below table-
 |
| Nomenclature of functional groups |
Step3- if functional group is
a suffix then removes ‘e’ from carbon chain name and add suffix.
Example- Propanone = Propan +
One
Where,
‘Propan’ comes from propane – ‘e’ and, ‘one’ comes from
ketone.
Step4- if the carbon compound
is unsaturated then ‘ane’ from the name is replaced by ‘ene’ or by ‘yne’ for
double or triple bond respectively.
Means ane for single bond,
ene for double bond and yne for triple bond.
Chemical Properties of Carbon Compounds
Carbon
compounds show different chemical properties and some of them are study here-
1. Combustion
Carbon burns in the presence of air (Oxygen i.e. O2)
to produce carbon dioxide (CO2), heat and light. This reaction is
oxidation reaction.
Saturated hydrocarbon gives clean flame while unsaturatedhydrocarbon give yellow flame with too much black smoke.
Example :-
C + O2 ---------> CO2 + Heat + Light
CH4 + O2 ------> CO2 + H2O + Heat + Light
CH3CH2OH + O2
--------> CO2 + H2O
+ Heat + Light
2. Oxidation
Removal of e-
is called oxidation. Burning of fuel or carbon compounds is complete
oxidation, but we can also see some incomplete oxidation in chemistry. Oxidizing
agents have the ability to add the oxygen to other substances.
CH3CH2OH + {(Alkaline KmnO4
+ Heat) or (Acidified K2Cr2O7 + Heat)} ---------> CH3COOH
Acidified Potassium Dichromate or Alkaline Potassium Permanganate is example of oxidizing agents.
3. Addition Reaction
Addition reaction are the reactions in which hydrogen
is added at double bond or triple bonds in unsaturated hydrocarbons in the
presence of catalyst like Nickel, Palladium.
R2C=CR2 + H2 + Nickel
Catalyst -------> R2CH-CHR2
Example:- Hydrogenation of vegetable oils with Nickel
as a catalyst.
4. Substitution reaction
Substitution reactions are the
reactions in which hydrogen atoms is replaced by other elements.
CH4 + Cl2 + Sun Light -------> CH3Cl + HCl
Some Important Carbon Compounds
Ethanol and Ethanoic Acid
Ethanol (C2H5OH) and
Ethanoic Acid (CH3COOH) are very valuable carbon compounds.
Ethanol and its Properties:
Ethanol (C2H5OH)
is liquid at room temperature with M.P. 156K and B.P. 351K. Ethanol is present
in all alcoholic drinks and soluble in water. Ethanol is good solvent so used
in many medicines preparations. These notes are published by www.ChemistryNotesInfo.blogspot.com
Reactions of Ethanol
1. Reaction with Sodium
When sodium is added to ethanol, it produces sodium
ethoxide and hydrogen gas.
2Na + 2C2H5OH ------à 2C2H5O-Na+
(sodium ethoxide) + H2
2. Reaction to produce unsaturated Hydrocarbon
When we heat ethanol at 443K in the presence of excess
concentrated sulphuric acid (H2SO4) produces ethene due
to dehydration of ethanol.
CH3CH2OH + Hot Conc. H2SO4
------à CH2=CH2 + H2O
Conc. Sulphuric acid act as dehydrating agent as it
removes water from ethanol.
Question – What is denatured alcohol?
Answer – ethanol (Alcohol) is used on large
scale in industries as solvent so to avoid any misuse of ethanol we add some
poisonous substances (like methanol) in it and also add some dyes to provide
blue color. This type of alcohol is known as denatured alcohol.
Question – Is alcohol used as Fuel?
Answer
– yes, As alcohol (like Ethanol) on burning in sufficient air gives energy, CO2
and H2O
Ethanoic Acid and Its Properties
Ethanoic
acid is also known as acetic acid, it belongs to carboxylic acid (weak acids)
group. Vinegar is prepared from 5-8% solution of acetic acid in water. Vinegar is
used on large scale for the preparation of pickles (Achar). Chemical formula of
ethanoic acid is CH3COOH.
Reaction of Ethanoic Acid
1. Esterification Reaction
Ester is produced, when ethanoic acid
get react with the absolute alcohol and acid catalyst is used to catalyse this
reaction.
CH3COOH (ethanoic acid) + C2H5OH
(ethanol) + acid catalyst --------> CH3COOC2H5 (ester)
Ester gives sweet smells and esters are used for many
purposes like in making perfumes, flavoring agents etc.
On treating ester with sodium hydroxide solution
(alkali) produces sodium salt of carboxylic acid and alcohol. This reaction is
called as saponification reaction as this reaction is used in the preparation
of soap.
CH3COOC2H5 + NaOH
------> CH3COONa +
C2H5OH
2. Reaction of Ethanoic Acid with Base
Ethanoic acid reacts with sodium
hydroxide (base) to produce water and salt. Sodium ethanoate also known as sodium acetate.
CH3COOH + NaOH ------> H2O + CH3COONa
3. Reaction of Ethanoic Acid with Carbonates
Ethanoic acid and carbonate reacts to
produce carbon dioxide, water and salt. This salt is commonly known as sodium
acetate.
2CH3COOH + Na2CO3 --------> CO2 + H2O + 2CH3COONa
4. Reaction of Ethanoic Acid with Hydrogen Carbonates
Ethanoic acid and hydrogen carbonate
reacts to produce carbon dioxide, water and salt. This salt is commonly known
as sodium acetate.
CH3COOH + NaHCO3 -------> CO2 + H2O + CH3COONa
Soaps and Detergents
Soap
Soap is used for cleaning purpose. As we
know, most dirt contains oil, so this dirt does not easily remove and also do
not easily dissolve in water.
Soap
molecules are potassium or sodium salt of long chain of carboxylic acids. Ionic
end of soap is hydrophilic so dissolve in water but long carbon chain is
hydrophobic so dissolve in oil. In this way soap molecules form a structure,
this structure is named as ‘micelles’.
To
form micelle hydrophobic end attach
to dirt ( or oil droplet) and hydrophilic end faces outside. This activity
creates emulsion in water. These micelles make dirt (or oil droplets) to
dissolve in water and at last wash out and as a result we get clothes clean.
Detergent
Detergent is also used for cleaning purpose. Soaps are not very
effective in hard water but detergents are very effective in hard water. Detergent
molecules are sulphonate or ammonium salts of long chain of carboxylic acids.
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