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Natural Science Forum / Physics / General Physics / July 2008How many atoms?
Hi group, How many atoms are in the body of a 100 kg human and what would be the total (appx) Mass of it? On Jul 4, 2:52 pm, student2...@gmail.com wrote: > Hi group, > > How many atoms are in the body of a 100 kg human Dr. Ed Uthman worked out the elemental composition of a 70 kg human body: http://web2.iadfw.net/uthman/elements_of_body.html Multiply all the masses in column 2 by 100/70 to calculate for a 100 kg body. Convert the masses top grams with the number 1000 (g/kg). Then divide each mass (in g) by the atomic weight (g/mole) of the element in column 1. Multiply all the numbers of moles by Avogadro's Number 6.02214179 x 10^23 mol-1 http://physics.nist.gov/cgi-bin/cuu/Value?na|search_for=abbr_in! This gives you the approximate number of each type of atom in a 100 kg body. Add them up. > and what would be the > total (appx) Mass of it? The total approximate mass of a 100 kg body is 100 kg. Separating it into its constituent atoms does not affect the mass, which is a conserved quantity under these conditions. Tom Davidson Richmond, VA On Jul 4, 1:52 pm, student2...@gmail.com wrote: > Hi group, > > How many atoms are in the body of a 100 kg human and what would be the > total (appx) Mass of it? Answer to second question is 100 kg. Doh. The answer to the first question depends on the empirical chemical formula for a human. You can look that up pretty easily. PD > On Jul 4, 1:52 pm, student2...@gmail.com wrote: >> Hi group, [quoted text clipped - 8 lines] > > PD That looks like a Fermi question to me. You can get a reasonable estimate by dividing the mass of the human body by the mass of a carbon atom. Oxygen is heavier, hydrogen is lighter, and there's other stuff, but most of it is not too far away from carbon. It won't be a precise result, but if you remember the conversion from an amu to a kilogram, it will be reasonably close and you won't have to look stuff up. Or you can look stuff up, get a precise answer, and then get a bodybuilder or an obese person for your model human. Composition changed, too bad. > > On Jul 4, 1:52 pm, student2...@gmail.com wrote: > >> Hi group, [quoted text clipped - 19 lines] > bodybuilder or an obese person for your model human. Composition > changed, too bad. Actually, there's quite a bit more oxygen than carbon. http://web2.iadfw.net/uthman/elements_of_body.html http://www.random-science-tools.com/chemistry/chemical_comp_of_body.htm http://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements#Human_body Yay! <snip> /BAH > Yay! > > <snip> > > /BAH Don't get used to it. Part of the reason I've been away is Uncle Al's "river of sh.t". And it hasn't improved much. The same people arguing about the same things they've been arguing about for... it has to be more than a decade by now. Arguing with them has some value in the sense of clarifying your own thought processes, but that only extends until they start all over again. Beyond that, what's the point? They don't get anything out of it. And they're powerless to affect the course of science, or science policy. Really, if they could change the course of science it would be because there's some merit in their ideas, and I wouldn't want to stand in the way of that. But I predict the woo-woos will die convinced they're right and scientists all over the world for the past hundred years or so are idiots, and their brave new theories are obviously right except that the brainwashed conventional scientific community, who've proved remarkably ready to change their basic ideas of nature in the past, can't accept anything new. Because they think the sum total of physics research can be found on sci.physics and the Waldenbooks book shelves-- they're not aware of the novel science that made it to the professional rags but not as far as the newspapers or pop sci books because they've never looked and have no intention of looking. Yes, I've noticed my ambiguous use of pronouns above. I trust that you can easily figure out what I meant. And I trust equally that critics will find the stupidest possible way to interpret it. And part of the reason I've been gone is that it's amazing how much time is freed up when I stay away from Usenet. >> On Jul 4, 1:52 pm, student2...@gmail.com wrote: >>> Hi group, [quoted text clipped - 15 lines] > result, but if you remember the conversion from an amu to a kilogram, it > will be reasonably close and you won't have to look stuff up. I was thinking the same thing, except I would use water (multiplying by 3 to get the number of atoms) instead of carbon.  SignatureJim E. Black (domain in headers) How to filter out stupid arguments in 40tude Dialog: !markread,ignore From "Name" +"<email address>" [X] Watch/Ignore works on subthreads On Jul 4, 2:52 pm, student2...@gmail.com wrote: > Hi group, > > How many atoms are in the body of a 100 kg human and what would be the > total (appx) Mass of it? Obviously the total body mass would be 100 kg precisely. (Because that is what you specified). Now with respect to your other question, the starting point would the percentage of body mass that is made of by water, second carbon, and later other elements. Please don't come here to have us do your homework for you. Harry C. |
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