Producer gas (carbon monoxide) is prepared by passing air over red-hot coke:Water gas (a m...

Producer gas (carbon monoxide) is prepared by passing air over red-hot coke:

Water gas (a mixture of carbon monoxide and hydrogen) is prepared by passing steam over red-hot coke:

For many years, both producer gas and water gas were used as fuels in industry and for domestic cooking. The large-scale preparation of these gases was carried out alternately, that is, first producer gas, then water gas, and so on. Using thermochemical reasoning, explain why this procedure was chosen.