CARBON (II) OXIDE (CARBON MONOXIDE)
What is Carbon monoxide?. Carbon monoxide is an odourless, tasteless and colourless gas, which is insoluble in water.
It is extremely poisonous.
Under no circumstances must the gas be inhaled or smelled.
It is not usually prepared in a school laboratory.
If need be, the gas should be prepared in a fume chamber.
Preparation of carbon monoxide
1.By dehydrating oxalic acid with hot concentrated sulphuric acid
Carbon monoxide is prepared with the help of oxalic acid and concentrated sulphuric acid as shown below.
Oxalic acid has the formula . Sulphuric acid reacts with oxalic acid and removes from it one molecule of water (both the hydrogen atoms, along with an oxygen atom).
The product left behind due to this reaction, is a molecule of carbon dioxide and a molecule of carbon monoxide.
The carbon dioxide can be removed by passing it through a concentrated solution of potassium hydroxide.
- Preparation of carbon monoxide by dehydrating formic acid
Formic acid has the formula HCOOH. Formic acid can also be dehydrated in a similar way by hot concentrated sulphuric acid.
Sulphuric acid removes two atoms of hydrogen and one atom of oxygen as a molecule of water from it, and leaves behind one molecule of carbon monoxide.
Carbon monoxide is produced whenever organic matter is burnt in a limited quantity of oxygen.
For this reason, it is found in the exhaust gases of motor vehicles, as well as in cigarette smoke. Indoor fireplaces can be a serious hazard if ventilation is poor.
It is prepared industrially (mixed with hydrogen) by passing steam over coke at temperatures above 900 ºC. The resulting gas mixture is known as water gas, and it is used as a fuel:
Chemical Properties of Carbon Monoxide
- a) Nature
Carbon monoxide is a neutral oxide. It is neither acidic nor basic.
- b) Stability
It is very stable and cannot be decomposed by heat.
- c) Combustibility
It is a combustible gas. It burns well in air or oxygen to form carbon dioxide. The formation of carbon dioxide is tested by passing it through a solution of lime water.
However, it is not a supporter of combustion,
- d) Reducing property
Carbon monoxide is a powerful reducing agent.
When CO is passed over heated metallic oxides, it takes away the oxygen to form carbon dioxide and reduces the oxides to their respective metals.