If you had a good scale, All you need to do is weight the stock. Then chuck it is a lathe and make some long ribbon-like swarf until you have what you think is enough. Then weigh the remaining stock. Assume the difference is the amount of aluminum removed. Yes the surface area is reduced but it is like close enough to just assume the weight loss is all aluminum
Then weigh the ribbons. If you made these very thin then there is a huge surface area and the added oxygen will make then weigh more. You should be able to find then mass of the oxygen. If you have ever used a good analytic balance like the ones in a university lab where students to lab work you can weigh a paper index card. Then write your name on it with a pencil and re-weight the card to find the weight of the pencil lead used to write your name. These scales are common in labs. What I'm describing is something no more complex thatwhat a first or second year chemistry student would do as a textbook exercise maybe 40 years ago. If I were a student, I'd be asked to guess the result, then go and do the experiment and see if I guessed right. So my guess... I think that the oxide film thickness will be hundreds of times or even thousands of times less than the thickness of the ribbons so the amount of oxidized aluminum is trivial and so is the amount ofheat generated. I could be right or wrong, one would need to do the experiment. But as said, this is a student-level experiment and all you need is a very nice analytic balance scale. I see that scales that can measure 0.1 milligram are cheap now in eBay On Wed, Jul 8, 2020 at 9:18 AM Gene Heskett <[email protected]> wrote: > On Monday 06 July 2020 00:43:30 Chris Albertson wrote: > > > On Sun, Jul 5, 2020 at 3:33 AM andy pugh <[email protected]> wrote: > > > You say this a lot, but I have never heard anyone else say it. What > > > is your source? > > > > THis might be a "Chemistry 101" question. It should be easy enough to > > figure out except that I last studied this stuff in the last 1970s > > > > We all know that burning carbon produces a lot of heat. The chemical > > equation is > > C + O2 --> CO2 -394 kJ / mole > > > > The corresponding equation of aluminum is > > 4Al + 3O2 --> 2Al2O3 -1676 kJ/mole > > Aluminum produces more heat per mole than carbon and also more heat > > per gram than carbon. It would make good fuel except for combustion > > stops once the oxide layer is formed. > > > > Next, I looked up the specific heat of aluminum. It is very close to > > 1.0 kJ / (Kg K). So it only takes 1 Joule to heat one gram of > > aluminum one degree K. > > > > So there is plenty of energy and the metal is also easy to heat. But > > what we don't know is the fraction of aluminum that is oxidized. You > > could figure this out if you had a good enough scale and could collect > > all the chips. We could see how much mass the chips gained from the > > added oxygen. > > Difficult to do since the chips would have to be collected in an inert > atmosphere, weighed, then exposed to normal air for perhaps 1 second, > then weighed again. 99% of the weight gain would be in the first > millisecond of normal air exposure. As would the temp gain. One rapidly > runs into the real world while trying to imagine the lab lashup to > measure that. And I don't think excedrin can fix that headache :) > > Long term alox vs weight story: I bought an Ohaus 505 powder scale in > the early '60's to weigh powder for reloading my own ammo with, for a > wildcat cartridge called the 30-06 Ackley-Improved, and which I have > subsequently burned up/used up 4 barrels shooting at about 5k round per > barrel. > > This scale has an aluminum pan that is stamped but was not given a > protective coating. Its a very good scale, accurate to about .05 gr. No > trouble at all seeing a single ball of H414 powder hitting the pan But > the gradual buildup of the oxide on this pan has caused it to gain > around .25 gr in the past nearly 60 years, and has required me to hit > its edge with a file to remove enough weight to restore its zero balance > point with the balance beam dead level. Not even cleaning it with a > green scotchbrite pad will restore that balance, I must file away a > teeny bit of alu. So the effect is there, but hard to measure without > the right tools, and an O-Haus powder scale is about as good as you can > get that is still affordable. > > IIRC it was close to a 90 dollar bill in 1963 or 1964. To put that in > scale, custom dies were still $16.50 from RCBS, and my original 20+ lb's > of cast iron framed Herters O frame press cost $14.95. > > Cheers, Gene Heskett > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
