Page 64 - Chemistry ICSE Class IX
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52 ICSE Chemistry – 9
Petrol/diesel + 2O (g) o CO (g) + 2H O(v)
2
2
2
(petrol/diesel are from air
mixtures of hydrocarbons)
During the manufacture of alcohol by fermentation
invertase
C H O (aq) + H O(l) o C H O (aq) + C H O (aq)
6
11
22
2
12
6
12
6
6
12
sugar in molasses glucose fructose
zymase
C H O (aq) o 2C H OH(aq) + 2CO (g)
6
5
12
2
6
2
glucose/fructose ethanol
During respiration by humans and animals
The exhaled air during breathing contains large quantity of CO .
2
This CO is produced during respiration in the body. For example,
2
glucose during respiration gets oxidised to CO and H O.
2
2
respiration
C H O 6 + 6O (g) o 6CO (g) + 6H O(l)
6
2
2
2
12
glucose
Plants respire during night. During respiration plants take in
Alcoholic Fermentation oxygen and give out carbon dioxide.
From chemical industry during decomposition of carbonates and
bicarbonates
Heating CaCO (limestone) to obtain CaO (lime)
3
heat
CaCO (s) o CaO(s) + CO (g)
3
2
limestone lime
Heating hydrogencarbonate (or bicarbonates) of certain metals to
obtain the corresponding metal carbonates.
heat
2NaHCO (s) o Na CO (s) + CO (g) + H O(v)
2
2
3
3
2
sodium sodium
hydrogencarbonate carbonate
During the natural decay of organic matter, such as dead plants and
animals.
Diagram of the carbon dioxide cycle
Based on the consumption and production of carbon dioxide, the following
diagram describes the carbon dioxide cycle:
Fig. 2.8 The carbon dioxide cycle
