Page 213 - ICSE Chemistry 8

Procedure
• Keep adding vinegar to the baking soda ll the last candle goes out.
• Now, light another candle outside the container and pour the invisible gas in the container on the
lighted candle.

Observa on: All the candle go out one by one star ng from the shortest to the tallest. The candle placed
outside the container also goes out when the invisible gas in the container is poured over it.
Conclusion: Carbon dioxide produced by the ac on of vinegar on baking soda puts out the fl ames as it
does not support combus on. Shortest candle in the container goes out fi rst as carbon dioxide is heavier
than air and se les in the lower part of the container. As carbon dioxide is heavier than air it could be
poured out like water.

Properties of Carbon Dioxide

Physical Properties

Following are the physical proper es of carbon dioxide.

• Carbon dioxide is an odourless and a colourless gas.
• It is slightly acidic in nature and is fairly soluble in water.

• It is a non-poisonous gas. However, if the concentra on of carbon dioxide in air is increased, it can
cause suff oca on.
• Carbon dioxide when cooled down to –78°C forms
Dry ice is used in the manufacturing
dry ice which is a snow-white solid. It is called dry ice
of products like plas cs, chemicals,
because on hea ng, it directly changes from a solid
beverages, pharmaceu cals and metals.
to a gas (sublimes) without passing through the liquid
phase to form gaseous carbon dioxide.

• It is denser than air.

Chemical Properties

Following are the chemical proper es of carbon dioxide.
• Carbon dioxide is a compound formed by covalent bonding of carbon and oxygen.
• It does not support combus on.

• It turns moist, blue litmus red which shows that carbon dioxide gas is acidic in nature.
• Carbon dioxide dissolves in water and forms carbonic acid.
CO 2 + H O H CO 3
2
2
Carbon dioxide Water Carbonic acid
• Carbon dioxide reacts with alkalis to form salt and water.
2NaOH + CO Na CO 3 + H O
2
2
2
Sodium hydroxide Carbon dioxide Sodium carbonate Water
2KOH + CO K CO 3 + H O
2
2
2
Potassium hydroxide Carbon dioxide Potassium carbonate Water
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