Carbon Monoxide

Carbon monoxide is formed by the incomplete oxidation of carbon. It is found in petrol fumes.

Preparation

Lab method

1.        Concentrated sulphuric acid is added to oxalic acid and heated. Dehydration occurs, and a mixture of carbon dioxide and carbon monoxide is formed.
Carbon monoxide is collected by the downward placement of water.
H₂C₂O₄ Δ (Conc. H₂SO₄) → H₂O + CO₂ + CO 
Carbon dioxide is absorbed by potassium hydroxide solution.
KOH + CO₂ → KHCO₃

2.         Concentrated sulphuric acid is added to formic acid and heated. Dehydration occurs, and the carbon monoxide formed is collected over water.
H · COOH Δ (Conc. H₂SO₄) → H₂O + CO

Sodium formate can also be used – first formic acid is liberated, then it is dehydrated

H · COONa + H₂SO₄ → NaHSO₄ + H · COOH
H · COOH Δ (Conc. H₂SO₄) → H₂O + CO

These preparations should be carried out in fume cupboards.

Properties

Physical

1. It is a colorless, odorless and tasteless gas.
2. It is slightly soluble in water.
3. It is highly poisonous.
4. Boiling point -192°C
5. Melting point -207°C

Chemical

1. It is a neutral oxide of carbon.
2. It is a stable compound.
3. It does not support combustion, but is combustible.

               2CO + O₂ → 2CO₂ + 135400 cal.

4. It reduces metal oxides at high temperatures.

               PbO + CO → Pb + CO₂

               CuO  + CO → Cu + CO₂

               Fe₂O₃ + 3CO → 2Fe + 3CO₂

5. It combines with chlorine in sunlight and in the presence of charcoal.

               CO + Cl₂ → COCl₂ carbonylchloride (phosgene)

6. At 200°C and 6-10 atmos. it combines with sodium hydroxide.

               NaOH + CO → H · COONa

7. It forms an addition product with copper (I) chloride in HCl or ammonia solution.

               CuCl + CO + 2H₂O → CuCl · CO · 2H₂O

8.  
1. With hydrogen, at 300°C, and over nickel, it forms methane.

  300°C, Ni

                                 CO + 3H₂ →  CH₄ + H₂O

2. With hydrogen, at 400°C, and zinc and chromium oxides it forms methyl alcohol.

                              CO + 2H₂ →  CH₃OH

Uses

1. As a fuel – producer of water gas
2. To manufacture phosgene, sodium formate, and methyl alcohol