[iScience]

so, a typical combustion rxn of a hydrocarbon is written in the general way

C_xH_y+ O₂ H₂O +CO₂

but in a combustion rxn aren't there CO's and other hydrocarbon intermediates that were a part of the starting hydrocarbon compound that just broke off? ie.. perhaps not all of the hydrocarbon turned into water and CO2, perhaps only a portion of the main hydrocarbon reacted and turned into water and CO2, won't we have left over intermediates such as those? if so, why then.. is it just written as h2o + co2?

[Borek]

It is a general reaction equation for COMPLETE combustion. For incomplete combustion you can have numerous byproducts.

[WW]

of course, if you have an open system it is likely that you first thermally breakdown some of the hydrocarbons to VOCs which  are given off as gas.  Like the other poster said, that is a general reaction for complete combustion.  Don't mistake useful simplifications as lies

[Enthalpy]

To compute the heat of combustion and the necessary amount of air, the equation suffices.

To evaluate pollutants undesired even in trace amounts, like NO_x, CO, polycyclic aromatics... it doesn't.