JAMB - Chemistry (1986 - No. 10)

When steam is passed through red hot carbon (like coke), the products formed are carbon monoxide (CO) and hydrogen gas H\(_2\), which is commonly referred to as "water gas". This reaction occurs because the high heat breaks the bonds in the water molecule, allowing the oxygen to react with the carbon to form carbon monoxide, while the hydrogen is released as a gas. 

Chemical equation: C (s) + H\(_2\)O (g) → CO (g) + H\(_2\) (g).