Class 10 Chemistry Carbon and Its Compounds Chemical properties of carbon compounds

Chemical properties of carbon compounds

 

1. Combustion

  • All the allotropic forms of carbon burn in the presence of oxygen releasing carbon dioxide along with heat and light.

  • The chemical equation for the carbon compounds undergoing combustion are as follows:

(i) C + O2 → CO2 + heat and light

(ii) C2H5 (Ethane) + O2 → CO2 + H2O + heat and light

(iii) C5H12OH (Pentanol) + O2 → CO2 + H2O + heat and light

  • Saturated hydrocarbons undergo combustion giving a clean flame. But in the presence of limited supply of air hydrocarbons produces a sooty flame as a result of incomplete combustion.

Gas stove at home has inlets for sufficient supply of oxygen and hence the mixture burns giving a clean blue flame. But if the inlets get blocked the fuel remains unburnt and hence the bottom part of the cooking vessels gets blackened.

Combustion of fossil fuels such as coal and petroleum containing nitrogen and sulphur leads to the formation of oxides of nitrogen and sulphur that acts as major pollutants in the environment

 Take a gas stove having clean inlets for sufficient supply of oxygen. Burn the stove and heat a spoon. The spoon will not get a deposition of a black layer.

Take another gas stove having blocked inlets and heat the spoon. Soon deposition of a black layer over the spoon can be easily observed due to insufficient supply of oxygen resulting in the production of unburnt carbon particles.

  

Fig. Experiment to prove that in limited supply of air hydrocarbons produces a sooty flame and deposits black layer on the utensils

  • Unsaturated carbon compounds will give a yellow flame releasing an enormous amount of black smoke. 

2. Oxidation

Carbon compounds gets readily oxidised on combustion. The following equation shows the conversion of alcohols to carboxylic acid.

 

 

3. Addition Reaction

  • During addition reaction an unsaturated hydrocarbon adds hydrogen to the reaction in the presence of catalysts.
  • Catalysts such as palladium or nickel proceed a reaction to a different rate without affecting the reaction to give saturated hydrocarbons.

  • This reaction is extensively used in the hydrogenation of vegetable oils containing long unsaturated carbon chains using a nickel catalyst.
  • Animal fats on the other hand have saturated carbon chains.

 

4. Substitution Reaction

A reaction in which one functional group or atom is replaced by another functional group or atom is called substitution reaction.

In the presence of sunlight addition of chlorine to hydrocarbons is a fast reaction that results in replacement of the hydrogen atoms one by one. This is an example of substitution reaction because chlorine replaces the hydrogen attached to the carbon atom in the hydrocarbon.

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