Chemical Properties of Carbon Compounds

Summary

 Carbon compounds undergo different types of chemical reactions.

Combustion:
All carbon compounds react with oxygen to produce heat and light along with carbon dioxide and water. This reaction of carbon with oxygen is called combustion.

Carbon Compound + Oxygen → Carbon dioxide + water + heat and light
CH4 + 2O2 → CO2 + 2H2O + Heat and light.
        •  Aliphatic compounds on combustion produce a non-sooty flame.
        •  Aromatic compounds on combustion produce sooty flame.

Oxidation:
Alcohols undergo oxidation in presence of oxidising agents like alkaline potassium permanganate 
or acidified potassium dichromate to form carboxylic acids. 
Example:
Ethyl alcohol on oxidation with alkaline potassium permanganate or acidified potassium dichromate gives acetic acid.
             CH3-CH2-OH    Alkaline KMnO 7 or Acidified K 2 Cr 2 O 7   CH3-COOH

Addition reaction:
A chemical reaction is said to be an  addition reaction if two substances combine and form a third substance. In general unsaturated hydrocarbons like alkenes and alkynes prefers to undergo addition reactions. 
In addition reactions molecules add across double bond or triple bond.  
Hydrogenation reaction involves the addition of hydrogen to unsaturated hydrocarbons in presence of catalyst like nickel or platinum to form saturated hydrocarbons.
Example:
Addition of hydrogen to ethene




Addition of hydrogen ethyne.
 CH ≡ CH + 2H2         Ni or Pt          CH3-CH3

Addition of halogens to alkenes.
CH= CH2 + X2 → CH2X - CH2

Substitution reaction:
A reaction in which an atom or group of atoms replaces another atom or group of atoms is called substitution reaction. Alkanes undergo substitution reactions. 
Example: 
Chlorination of methane in presence of sunlight gives a mixture of products like methyl chloride, 
methylene chloride, chloroform and carbon tetrachloride.
 
CH4 + Cl2      Sunlight       CH3Cl + HCl
CH3Cl+Cl2         Sunlight        CH2Cl2 + HCl
CH2Cl2+Cl2       Sunlight        CHCl3+HCl
CHCl3+Cl2       Sunlight         CCl4+HCl

Polymerization reaction:
Alkenes and alkynes at higher temperatures under polymerization to form bigger molecules called as polymers.
Example:
Ethene at 400 °C undergoes polymerization to form polyehene.

nCH= CH2 → [-CH-CH- CH- CH2-]n

Cracking:
At higher temperatures in absence of air higher hydrocarbons breaking into smaller hydrocarbons. This process is called cracking.
Example:
 
              C10H22           Cracking at 600 - 700          C6H14  +  C4H8

Videos

  • LearnNext Video

  • YouTube Video

  • YouTube Video