Heating of Calcium carbonate
Fermentation of Sugar
Carbon dioxide (CO2):
Carbon dioxide is present in the Earth's atmosphere to an extent of 0.03% by volume. Carbon dioxide is produced during
combustion of fossil fuels, respiration, fermentation and volcanic eruptions.
Carbon dioxide is a powerful greenhouse gas, and it is all the extra gas from fossil fuels, together with deforestation, that is causing global warming.
Preparation
Carbon dioxide may be prepared by the complete combustion of carbon, hydrocarbons, carbon monoxide etc.
By heating carbonates of alkaline earth metals and heavy metals or bi-carbonates of alkali metals produces carbon dioxide
Large quantities of carbon dioxide are obtained as by–product during the manufacture of lime by burning limestone in lime kilns and during the manufacture of alcohol by the fermentation of sugar.
Properties
- CO2 is a colorless stable gas with a faint pungent smell, is heavier than air and is fairly soluble in water.
- CO2 can be easily liquefied and solidified under pressure (50–60 atmospheres). Solidified carbon dioxide looks like ice and is called dry ice.
- Carbon dioxide is neither combustible nor a supporter of combustion. Certain very active metals, e.g., magnesium, sodium and potassium continue burning in a jar of CO2 and reduce it to elementary carbon.
- CO2 is acidic in nature forms carbonic acid when dissolved in water and forms carbonates and bi–carbonates when reacted with Strong alkalis.
- CO2 with lime water forms calcium carbonate, is used in detection of CO32–
and HCO3− ions in any salt/salt mixture.
- CO2 is utilized by plants to produce glucose by photosynthesis.
Uses of CO2
- In the manufacture of aerated water (soft drinks).
- As a fire extinguisher.
- For the manufacture of sodium carbonate and sodium bicarbonate by Solvay process.
- In the form of dry ice it is used as a refrigerant (coolant) for perishables in food industry e.g., for fish, ice creams etc.
- For artificial respiration (35%CO2 + 5%O2) for the victims of CO poisoning.