# What is the oxidation state of the carbon atoms in acetylene?

Jan 16, 2016

Acetylene is a quite reduced form of carbon; the carbons each have a $- I$ oxidation state.

#### Explanation:

Note that acetylene is neutral and while we can speak of the oxidation numbers of its atoms, we cannot speak of the molecule's oxidation state.

If we break up the $C - H$ bonds we get $2 \times {H}^{+}$, and ${\left\{C \equiv C\right\}}^{2 -}$ (carbon is more electronegative than hydrogen, so when you (for the purposes of assigning oxidation number) break this bond you put a formal $+ 1$ charge on hydrogen, and a formal $- 1$ charge of carbon.

In fact, the acetylide unit ${\left\{C \equiv C\right\}}^{2 -}$ occurs as calcium carbide, $C a {C}_{2}$, which is an important industrial feedstock.

More reduced forms of carbon include ethylene, ${H}_{2} C = C {H}_{2}$, ${C}^{- I I}$, and the methylene unit of a carbon , $- C {H}_{2}$, ${C}^{- I I}$. Oxidation state assignments are of course formalisms; they do not have real significance other than what we assign for them. When we break a $C - C$ bond in such a process, we conceive we get $2 \times C \cdot$, i.e. neutral carbon radicals.