how do you know if a combustion equation is complete or incomplete?

Answer 1

You know if a combustion equation is complete if the only products are water and carbon dioxide. If there's anything else, it's incomplete combustion. Incomplete combustion happens when there's not enough oxygen for the combustion to be complete. Look below for the equations:


Complete combustion:

CxHy + (x + y/4)O2 → xCO2 + (y/2)
H2O

Incomplete combustion:

CxHy + O2 → CO2 + H2O + CO (I can't balance this one because there are more products that I don't know about that can be formed, depending on how complete or incomplete the reaction was)

Answer 2

If it is balanced, the EQUATION is always complete.

If you are asking if a particular COMBUSTION is complete, you have to look at the moles of fuel and the moles of oxidizer and verify they are the same as the equation.