Water Gas

Water gas is a synthesis gas, containing carbon monoxide and hydrogen. It is a useful product but requires careful handling because of the risk of carbon monoxide poisoning. The gas is made by passing steam over a red-hot carbon fuel such as coke:

H₂O + C → H₂ + CO (ΔH = +131 kJ/mol)

The reaction is endothermic so the fuel must be continually re-heated to keep the reaction going. In order to do this, an air stream, which alternates with the vapor stream, is introduced for the combustion of carbon to take place.

O₂ + C → CO₂ (ΔH = −393.5 kJ/mol)

Theoretically to make 6 L of water gas, 5 L of air is required.

Or alternatively to prevent contamination with nitrogen, energy can be provided by using pure oxygen to burn carbon into carbon monoxide.

O₂ + 2 C → 2 CO (ΔH = −221 kJ/mol)

In this case 1 L of oxygen will create 5.3 L of pure water gas