# What is the empirical formula for kerosene?

Kerosene is a blend of hydrocarbons, so it doesn't have one chemical formula. But I'd like to find an (approximate) empirical formula giving the ratios carbon and hydrogen.

I haven't found anything online, and beggars can't be choosers. My actual interest is in RP-1. There is a NIST document (archive) on its thermophysical properties which gives a spectroscopic breakdown on pages 29–32 showing that even this highly refined kerosene is mind-bogglingly complex chemically.

On p. 28 of the NIST document linked in the question, there is a surrogate mixture formulation of 14 hydrocarbons which closely approximates RP-1. Its empirical formula is $\mathrm {C_{11.8}H_{23.0}}$, and this should be close enough for any sort of kerosene. The properties of this surrogate are given on p. 7.

This means that burning $\pu {1 kg}$ of kerosene in air produces about $\pu {3.15 kg}$ of $\ce {CO2}$ and $\pu {1.26 kg}$ of $\ce {H2O}$ with the extra mass, $\pu {3.41 kg}$, coming from oxygen. Alternately, if you have $\pu {1 kg}$ of a perfect stoichiometric mix of RP-1 and liquid oxygen, burning it would produce $\pu {715 g}$ of $\ce {CO2}$ and $\pu {285 g}$ of $\ce {H2O}$.