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
Famous quotes containing the words water and/or gas:
“Here is no water but only rock
Rock and no water and the sandy road
The road winding above among the mountains
Which are mountains of rock without water
If there were water we should stop and drink
Amongst the rock one cannot stop or think”
—T.S. (Thomas Stearns)
“Shielded, what sorts of life are stirring yet:
Legs lagged like drains, slippers soft as fungus,
The gas and grate, the old cold sour grey bed.”
—Philip Larkin (1922–1986)