Chapter 6, Problem 6.90QP

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

$\text{C}(s)+\frac{1}{2}{\text{O}}_2(g)\stackrel{}{\to }\text{CO}(g)$

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

$\text{C}(s)+{\text{H}}_2\text{O}(g)\stackrel{}{\to }\text{CO}(g)+{\text{H}}_2(g)$

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.