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Carbon dioxide - Preparation, Properties, Structure, Uses | Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail |

Chapter: 12th Chemistry : p-Block Elements-I

Carbon dioxide

Carbon dioxide occurs in nature in free state as well as in the combined state. It is a constituent of air (0.03%). It occurs in rock as calcium carbonate and magnesium carbonate.

Carbon dioxide:

Carbon dioxide occurs in nature in free state as well as in the combined state. It is a constituent of air (0.03%). It occurs in rock as calcium carbonate and magnesium carbonate.


Production

On industrial scale it is produced by burning coke in excess of air.

2CO + O2 → 2CO2

ΔH = 394 kJ mol-1

Calcination of lime produces carbon dioxide as by product.

CaCO3 → CaO + CO2

Carbon dioxide is prepared in laboratory by the action of dilute hydrochloric acid on metal carbonates.

CaCO3 + 2HCl → CaCl2 + H2O + CO2


Properties

It is a colourless, nonflammable gas and is heavier than air. Its critical temperature is 31 C and can be readily liquefied.

Carbon dioxide is a very stable compound. Even at 3100 K only 76 % decomposes to form carbon monoxide and oxygen. At still higher temperature it decomposes into carbon and oxygen.


Reducing behaviour:

At elevated temperatures, it acts as a strong reducing agent. For example,

CO2 + Mg → 2MgO + C

Water gas equilibrium:

The equilibrium involved in the reaction between carbon dioxide and hydrogen, has many industrial applications and is called water gas equilibrium.

CO2 + H2 ↔ CO + H2O Water gas

Acidic behaviour:

The aqueous solution of carbon dioxide is slightly acidic as it forms carbonic acid.

CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3-


Structure of carbon dioxide

Carbon dioxide has a liner structure with equal bond distance for the both C-O bonds. In this molecule there is one C-O sigma bond. In addition there is 3c-4e bond covering all the three atoms.



Uses of carbon dioxide

·           Carbon dioxide is used to produce an inert atomosphere for chemical processing.

·           Biologically, it is important for photosynthesis.

·           It is also used as fire extinguisher and as a propellent gas.

·           It is used in the production of carbonated beverages and in the production of foam.


Tags : Preparation, Properties, Structure, Uses Preparation, Properties, Structure, Uses
Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail


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