# Your reactants are a hydrocarbon and oxygen. Your products are carbon dioxide and water. What type of reaction do you have?

Feb 28, 2016

A combustion reaction, which is (i) a special case of redox reactions, and (ii) which drives our industrial society.

#### Explanation:

We can give the general combustion reaction for an alkane as:

${C}_{n} {H}_{2 n + 2} + \frac{3 n + 1}{2} {O}_{2} \rightarrow n C {O}_{2} + \left(n + 1\right) {H}_{2} O + \Delta$

Is this balanced? If it's not, it should be!

Carbon is oxidized up to its maximum oxidation state $+ I V$ (from FORMAL oxidation states of $- I I I$ and $- I I$ in the alkane); zerovalent oxygen gas is reduced to a $- I I$ oxidation state. These reactions are strongly exothermic in that while we break STRONG $C - H$ and $O = O$ bonds, we make STRONGER $C = O$ and $O - H$ bonds, with a net release of energy.

The reaction represents complete combustion in that all of the carbon reactant is oxidized to $C \left(I V\right)$. Under conditions of incomplete combustion (for instance in the internal combustion reaction or a furnace) SOME of the hydrocarbon could be oxidized to $C \equiv O$ or particulate $C$.