do you mean chemical formula?
That's pretty vague, since "soot" is left behind after combustion of a wide variety of substances, each producing a different mix of products. But they are all mostly just carbon.
Maybe google can provide you with some further information on the types of soot and their composition.
What is the chemical equations for soot?
2 answers
There are MANY chemical equations for the formation of soot. The exact formula depends on what is being burned and how much oxygen is used. Soot is, for the most part, amorphous carbon and it is formed when an organic material is burned in less oxygen than is need to convert all of the carbon in the organic compound to CO2. There some sites on the internet that try to write an equation for the formation of soot but, in my opinion, all of them fall short. My suggestion, if you want an equation, is to google the question. You will find several answers depending upon what is being used as a starting material.