Is acetylene or propane more likely to produce soot and why?

Answer 1

propane will produce less soot.

"burning" is the process of combining something with oxygen (O2). "Soot" is chunks of carbon atoms bonded to each other and therefore NOT bonded to oxygen atoms. A clean burning substance, like propane, will combine all of its carbon atoms with oxygen atoms, and all of its protons with oxygen atoms, and et cetera. This means no chunks of carbons bonded to other carbons will occur.

The man is right: carbon fuels with multiple bonds present will burn dirtier than those with only single bonds present. A multiple bond, like that in acetylene, will allow for the carbons on it to form bonds to other carbons easier.

In chemical terms, I think this is best presented in terms of entropy.

Think of it this way: the carbons on acetylene and propane both form new C-C bonds when making soot, so the enthalpy (bond forming energy) of burning is similar. However, having a multiple bond present vastly reduces the entropy cost for forming new C-C bonds. In order to form a new C-C bond, there needs to be "extra" electron density near one of the carbons, so it can attack and bond to the other carbon. The carbons on the multiple bond don't need to go track down electron density in a gaseous cloud of carbon and oxygen: the bond means they have it with them already. With enough heat around, the triple bond will just attack any carbon nearby, and form soot.

Answer 2

That is easy. The triple bond of acetylene allows for polymerization into chains of carbon to make soot.

Answer 3

propane is a colorless, odorless, non-toxic gas burns cleaner than gasoline, diesel and other fossil fuels "because it emits no sulfur dioxide or particulates". If unintentionally released in its liquid form, it quickly evaporates and does not contaminate soil or groundwater. Propane is environmentally friendly.

Answer 4

Acetylene...it is a rather poor fuel on it's own, does not combust well unless aided by oxygen.