Remember the water-gas shift reaction (C + H₂O ⇌ CO + H₂) and steam reforming of hydrocarbons. These are key industrial reactions that produce carbon monoxide. The reaction of CO₂ with water is a simple acid-base reaction forming carbonic acid.
Let's analyze the reaction of water (steam at high temperatures) with each substance.
(A) Reaction with Carbon (C): At high temperatures, steam reacts with coke (carbon) to produce a mixture of carbon monoxide and hydrogen, known as water gas.
C(s) + H$_2$O(g) $\rightarrow$ CO(g) + H$_2$(g)
This reaction produces CO.
(B) Reaction with Carbon Dioxide (CO$_2$): Carbon dioxide reacts with water to form carbonic acid. There is no reaction that produces carbon monoxide. In fact, the reverse water-gas shift reaction consumes CO.
CO$_2$(g) + H$_2$O(l) $\rightleftharpoons$ H$_2$CO$_3$(aq)
This reaction does NOT produce CO.
(C) Reaction with Propane (C$_3$H$_8$): The steam reforming of hydrocarbons like propane is a common industrial process to produce hydrogen and synthesis gas (a mixture of CO and H$_2$).
C$_3$H$_8$(g) + 3H$_2$O(g) $\rightarrow$ 3CO(g) + 7H$_2$(g)
This reaction produces CO.
Therefore, water does not produce CO when reacting with CO$_2$.
