Carbon Monoxide

Carbon Monoxide, CO

Preparation.

• Direct oxidation with limited oxygen/air: $2C(s) + O_2(g) \xrightarrow{\Delta} 2CO(g)$
• Laboratory-scale: dehydrating formic acid ($HCOOH$) with concentrated $H_2SO_4$ at 373 K releases water and CO.
• Commercially — passing steam over red-hot coke gives water gas (or synthesis gas), a mixture of CO and $H_2$:

• Passing air (instead of steam) over hot coke gives producer gas, a mixture of CO and $N_2$:

Both water gas and producer gas are important industrial fuels; the CO in them undergoes further combustion to $CO_2$, releasing heat.

Properties. CO is a colourless, odourless gas, almost insoluble in water. It is a powerful reducing agent, reducing almost every metal oxide except those of the alkali metals, alkaline earth metals, aluminium, and a few transition metals — a property put to industrial use to extract metals from their ores:

Bonding. The C–O bond in CO is a triple bond — one $\sigma$ and two $\pi$ bonds — with a lone pair remaining on carbon: $:C \equiv O:$. Because of this lone pair, CO acts as an electron-pair donor and reacts with many metals on heating to form metal carbonyls. …