It's all about >>>>>>>>> CHEMISTRY!!!!!: Breath it out....carbon dioxide!!

During respiration, we breath out carbon dioxide. Carbon dioxide is only 0.04% in atmosphere. Carbon dioxide is a molecule with the molecular formula CO2. The linear molecule consists of a carbon atom that is doubly bonded to two oxygen atoms, O=C=O.Although carbon dioxide mainly consists in the gaseous form, it also has a solid and a liquid form.

Description of carbon dioxide

Chemical Formula: CO2

Molecular weight :44.01

Colour: Colourless

Melting Point : -55.6 degC
Boiling Point : -78.5 degC
Density : 1.977

1. Carbon dioxide is a linear covalent molecule.

2. Carbon dioxide is an acidic oxide and reacts with water to give carbonic acid.

CO2 + H2O ==> H2CO3

3. Carbon dioxide reacts with alkalis to give carbonates and bicarbonates.

CO2 + NaOH ==> NaHCO3 (Sodium BiCarbonate )
NaHCO3 + NaOH ==> Na2CO3(Sodium Carbonate) + H2O

4. It is soluble in water, in ethanol and in acetone.

5. Carbon dioxide can change the pH of water. Carbon dioxide dissolves slightly in water to form a weak acid called carbonic acid, H2CO3, according to the following reaction:

CO2 + H2O --> H2CO3

After that, carbonic acid reacts slightly and reversibly in water to form a hydronium cation, H3O+, and the bicarbonate ion, HCO3-, according to the following reaction:

H2CO3 + H2O --> HCO3- + H3O+

This chemical behaviour explains why water, which normally has a neutral pH of 7 has an acidic pH of approximately 5.5 when it has been exposed to air.

6. Carbon dioxide is use in soft drinks and beer to make them fizzy.

7. Carbon dioxide released by baking powder or yeast makes cake batter rise.

8. Fire extinguishers use carbon dioxide because it is denser than air. Carbon dioxide can blanket a fire, because of its heaviness. It prevents oxygen from getting to the fire and as a result, the burning material is deprived of the oxygen it needs to continue burning.