Page 217 - ICSE Chemistry 8

Carbon monoxide is produced in domes c and industrial ovens. It is also emi ed from automobile engines
which run on petrol and diesel.
Properties of Carbon Monoxide

• Carbon monoxide is a highly poisonous gas.
• It is a colourless and odourless gas, so its presence cannot be detected. This makes it highly
dangerous.

• It is very sparingly soluble in water.
• It burns in air with a blue fl ame to form carbon dioxide.
• It is a reducing agent. It reduces heated oxides of metals like zinc, iron, lead and copper to their
respec ve metals and forms carbon dioxide.

ZnO + CO Zn + CO 
2
Zinc oxide Carbon monoxide Zinc Carbon dioxide

Fe O 3 + 3CO 2Fe + 3CO 
2
2
Iron(III) oxide Carbon monoxide Iron Carbon dioxide
This property of carbon monoxide makes it useful in the extrac on of metals from their ores.
Poisonous Nature of Carbon Monoxide

Carbon monoxide is a highly poisonous gas. Even if 1% carbon monoxide by volume is inhaled, it can kill a
person in a few minutes. When carbon monoxide enters the blood stream, it combines with haemoglobin
present in the blood (red blood corpuscles or RBCs) to form a compound called carboxyhaemoglobin.
Carboxyhaemoglobin does not allow oxygen to be absorbed by haemoglobin. So haemoglobin is not
able to carry oxygen to various parts of the body. Lack of oxygen in the body results in a condi on called
asphyxia which may cause suff oca on, unconsciousness and even death.
That is why it is dangerous to sleep in a closed room with a coal fi re burning as incomplete burning of coal
leads to the forma on of carbon monoxide. Due to the same reason, it is dangerous to run a car engine
in a closed space (garage).

Precautions to be Taken to Avoid Carbon Monoxide Poisoning

Following precau ons should be taken to avoid carbon monoxide poisoning.
• Do not sleep in a closed room with a coal fi re burning.
Thirst for Knowledge
• Do not run a car engine in a closed space (garage).
A lime kiln is used to produce
• Do not sleep near lime kilns as the air around these kilns
quicklime through calcina on of
may have large traces of carbon monoxide. limestone.

• Smoke from burning tobacco contains small traces of
carbon monoxide. It is dangerous for the respiratory system of the smokers and also the passive
smokers who inhale the smoke.
• At places where carbon monoxide concentra on is on the higher side, wear gas masks that absorb
carbon monoxide. The masks are made of hopcalite (a mixture of metallic oxides) which oxidises
carbon monoxide to carbon dioxide.

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