# Is OH + CO → CO2 + H an elementary reaction?

Is

$$\rm OH + CO \longrightarrow CO_2 + H$$

an elementary reaction? How could I tell?

I could break the reaction into

$$\rm OH\ (+ M) \longrightarrow O + H\ (+ M)$$

$$\rm CO + O \longrightarrow CO_2$$

but I don't know if the former is witnessed.

• $\ce{OH}$ and $\ce{H}$ arent really stable species that actually exist – Pritt says Reinstate Monica May 21 '17 at 17:05
• The only way is to perform some experiments. Just writing down the stoichiometric equation is not really informative as to the mechanism; for example $\ce{H2 + Cl2\rightarrow 2HCl}$ proceeds by a radical chain reaction and not as implied by this equation. Incidentally, the species H and OH are well known; OH is stable enough to be measure in the atmosphere and is important in atmospheric chemistry. – porphyrin May 21 '17 at 18:35
• Another note on OH: while OH can be measured in the atmosphere by very sensitive techniques, it is indeed extremely unstable, and exists at levels of around 0.1 ppt, or 10^6 molecules per cc! It's atmospheric lifetime is on the order of 0.1 seconds, and as it is produced by sunlight, levels drop to very close to zero at night. – airhuff May 21 '17 at 19:51
• @ airhuff re OH, nevertheless at $0.1$ sec OH is a hugely long lived radical :) – porphyrin May 22 '17 at 8:07