I saw a movie a while back called “Smoke” in which one character (played by William Hurt) tells a story to another character (Harvey Keitel) about someone who weighed smoke. He said that the smoke was weighed by first weighing a cigar, then smoking it and carefully saving all the ashes and after extinguishing it, he kept the butt. He then weighed the ashes and butt and subtracted that weight from the weight of the whole cigar, and the difference was the weight of the smoke. I’ve thought about this for a long time, and can’t decide if it’s logical or not. Can someone give me some input on this?? Thanks
All the matter that isn’t in those ashes has to go somewhere. It goes into the smoke. So yes, I’d say it’s logical.
Yeap, sound like a good method.
Cigars contain a lot of organic chemicals that convert into gaseous compounds during combustion. You should also get some water vapour and particulates (carbon based bits from incomplete combustion).
It depends on your definition of smoke. Smoke is a visible suspension of particulates in a gas. If you include all the non-visible combustion products as part of the definition then this method would work.
If you were just after particulates, than the value obtained would be high.
An obvious source of error is an increase in mass of the butt by absorption of moisture from the smoker, from mouth and respired, leading to a low value for your result.
I believe antechinus is right - it depends on what you consider to be smoke. Things like carbon dioxide and water vapor are probably not among everyone’s definition, and they are likely a substantial part of the combusted mass. So I’d say the OP method is suspect.
The person in the story was Sir Walter Raleigh.
Wouldn’t the mass of oxygen atoms in the air also factor in?
Yes. Oxygen combines with the ash and the ‘smoke’.
When you subtract the mass of the ash (the value of which is augmented by the oxygen), it gives you a low value for the smoke mass.
Furthermore, the smoke also contains oxygen, which means the value obtained for the smoke mass is even more underestimated if the mass of oxygen combined withthe smoke is neglected.
I kind of wonder what the point of weighing the smoke is if you don’t also measure its volume somehow.
Except, I guess it gives you an excuse to smoke a cigar.
You need to be careful here, about what ash actually is. Sure, it’s “what’s left over”, but what’s in it? Generally it’s oxides of Si, P, Ca, Fe, Cu, Zn, K, etc. You also need to consider what compounds those elements were bound into before the combustion. They almost certainly weren’t in their elemental form, and was a net quantitly of O absorbed or released in transforming them to their final state?
On second thought, “oxides” doesn’t describe it well enough. You also need to consider various other forms, such as carbonates and nitrates.
If the smoke includes gases, then it doesn’t have any fixed volume.
Okay, then I guess I wonder what the point is unless you also measure its temperature/pressure/volume or some combination thereof.
I am thinking mainly organic ash (char - especially near the butt). I suppose the temperature would be high enough to remove much of the organics from the ash, but you would need a muffle furnace if you wanted to remove all the organics.
So the ash would contain some carbon, compounds of incomplete oxidation of carbon plus sulphates and nitrates, as well as all the mineral oxides.
I suppose that depends on the temperature of the cigar.
Why is any of that important. The purpose of the experiment is basically to show conservation of mass. Measuring mass is the only thing of iterest in this case…and it’s perfectly useful by itself.
I don’t see how one can say mass is meaningless property without the inclusion of the others you mention. When you step on a scale, and you see your weight, do you say, “But that doesn’t mean anything since I don’t know my volume!” ?
How? The experiment as stated assumes the conservation of mass to begin with.
Wow, you all went way deep on this one!! Thanks everyone for your responses, but now I’m confused as hell!! : )
But, what about the smoke that the smoker inhales? Doesn’t some of that smoke stay inside the smoker?
It sure does, but they’re not weighing the smoker.
The weight of smoke is called ‘phlogiston.’
I was amused by this theory as a youngster. It’s akin to alchemy:
http://www.english.upenn.edu/~jlynch/Frank/Contexts/phlog.html
So