Page 214 - ICSE Chemistry 8

On passing excess of carbon dioxide through alkalis, a soluble bicarbonate is produced.
Na CO 3 + CO 2 + H O 2NaHCO 3
2
2
Sodium carbonate Carbon dioxide Water Sodium bicarbonate
K CO 3 + CO 2 + H O 2KHCO 3
2
2
Potassium carbonate Carbon dioxide Water Potassium bicarbonate
When carbon dioxide is passed through lime water, it turns lime water milky. This happens due to the
forma on of calcium carbonate which is insoluble in water. However, on passing excess of carbon dioxide
gas through the solu on, the milkiness disappears which occurs due to the forma on of a soluble
bicarbonate.

Ca(OH) 2 + CO CaCO 3 + H O
2
2
Lime water Carbon dioxide Calcium carbonate Water
(insoluble)
CaCO 3 + H O + CO Ca(HCO )
2
2
3 2
Calcium carbonate Water Carbon dioxide Calcium bicarbonate
(soluble)
• Carbon dioxide reacts with metallic oxides and forms metal carbonates.

Na O + CO Na CO 3
2
2
2
Sodium oxide Carbon dioxide Sodium carbonate
MgO + CO MgCO 3
2
Magnesium oxide Carbon dioxide Magnesium carbonate
Uses of Carbon Dioxide

Following are the uses of carbon dioxide.
• Aerated drinks: Carbon dioxide is used to manufacture aerated drinks. On dissolving carbon
dioxide gas in water, soda water is formed. Soda water has a sharp and sour taste which is due to
the forma on of carbonic acid. Sugar, colour and fl avour are mixed with soda water to prepare a
so drink.
• Dry ice: Solid carbon dioxide is called dry ice. It acts as a good refrigerant and is used to preserve
food items such as fruits, vegetables, meat, etc. Grains are also kept in an atmosphere of carbon
dioxide in order to prevent them from insect a acks and keep them in a good condi on for a long
dura on.

• Fer lisers: Carbon dioxide and ammonia are heated at 200°C under high pressure to prepare urea
which is an important nitrogenous fer liser.
• Carbogen: Carbogen is a mixture of 5% carbon and 95% oxygen. It is used for ar fi cial respira on.
It is given to pa ents who are suff ering from pneumonia, poisoning, drowning, etc.

• Washing soda and baking soda: Carbon dioxide is used to manufacture washing soda (sodium
carbonate) and baking soda (sodium bicarbonate).
• Baking industry: Carbon dioxide is used in the baking industry to make the dough rise and become
light. Baking powder is a mixture of baking soda and potassium hydrogen tartrate. On adding
baking powder to the dough, the ingredients of baking soda react to produce carbon dioxide.

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