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This video started a good discussion over on my friends feed. So far no one has answered it and I dont want to give away the answer to anyone else (please CW your answers) but the question is this:
Why is it when you burn a piece of steel wool it gets heavier, but if you burn a log it gets lighter.
@DuchessOfMars that is a small part of the answer, but not the majority of it.
tentative answer
@freemo I would say the burning of the steel wool is an oxidization process -- the Fe combines with air's O2, and the Oxygen is absorbed into the metal mesh, adding to it's mass.
Normal combustion might make solid carbon compounds into CO2 and CO, which are gases and will leave the burning materials. Less mass resulting.
tentative answer
@design_RG bingo.. both are oxidative process though, but yes, thats exactly it.
One small detail the combustion of a log losses weight through two ways.. one is the carbon lost and is carried away by oxygen, that is the majority of its mass. A small portion of its mass, but significant, is the same reaction also creates new water that didnt exist priot to the reaction, that water is hot and in the form of steam and is also carried away.
But yes mostly the carbon.
An added detail.. if you counted the total mass of the log after burning to include the carried away water and CO2 then exactly like the steel wool it would in fact be more massive
tentative answer
@freemo > the same reaction also creates new water
? Really? Where did the H came from? Broken down hydrocarbon compounds?
tentative answer
@design_RG well in trees its a bit tricky because there are many different things burning and all of them produce water.. in fact most forms of combustion, though not all do.
I think the simplest way to explain it (though keep in mind it is an oversimplification) is to just reverse the equation for photosynthesis. Look at its unbalanced form:
H20 + CO2 -> C6H12O2 + O2
So basically in this case it would come from the sugars... though in reality in wood the sugards arent there anymore they converted to wood oils and alcohols... But every sort of combustion in organic chem is pretty much going to have a H2O by product...
In wood it would mostly be terpine which is C10H18O plenty of hydrogen in there too.
Here is the really cool part though,w hen you reverse it.. when a tree grows, where does all of its mass come from... The air...
@freemo Gnomes, right?
@freemo For more fun these experiments should be performed in airtight chamber with manometer.
https://commons.wikimedia.org/wiki/File:Busch_Werke_v1_p_235.jpg
@freemo At standard temperature and pressure,
the oxides of iron remain solid, while the oxides of carbon are gaseous and dissolve into the atmosphere.
Rust binds atmospherical oxygen,
carbon oxides release carbon.
https://commons.wikimedia.org/wiki/File:Busch_Werke_v1_p_235.jpg
@tatzelbrumm
Yup thats the majority of the eeight. Only part you forgot is that water is also generated in the reaction and released as steam.
