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Why is CO2 the correct answer, the answer should be energy/heat + CO2 + H2O? The "burning" of fat in oxygen to CO2 and H2O is exothermic.
by s0rce 9y ago
Why is CO2 the correct answer, the answer should be energy/heat + CO2 + H2O? The "burning" of fat in oxygen to CO2 and H2O is exothermic.
- Xophmeister 9y agoTFA does say "energy/heat + CO2 + H2O", but most of the output in terms of mass -- which is what one is interested in when it comes to losing weight -- is carbon dioxide.
- mtzaldo 9y agoDoes this means that we can "control" entrophy in the universe by controlling the CO2?
- colechristensen 9y agoThe fat molecules burned usually have about twice as many hydrogen atoms as carbon atoms so you end up with about as many CO2 molecules as H2O molecules. Carbon weighs about 14 times as much as hydrogen and most of the oxygen in both comes from the atmosphere. So when you lose weight, 7 parts go to CO2 and 1 part goes to water. A very very tiny proportion goes to energy with mass-energy equivalence.
- zimbu668 9y agoFrom the abstract: "Most people believed that fat is converted to energy or heat, which violates the law of conservation of mass."
- orblivion 9y agoBut not the conservation mass-energy. What's to say we're not burning off our fat in a nuclear reaction? :-D
- colechristensen 9y agoChemical reactions undergo the same mass loss as nuclear reactions. A fat molecule weighs very slightly more than the sum of it's parts. The resulting water and carbon dioxide products will weigh less than the reactants by exactly the amount of energy released. It's just much more difficult to notice because the amount of energy released is as much less.
- gwright 9y agoIs this true? I was under the impression that the excess energy is due to the different bond energies of the input and output molecules and not due to mass to energy conversion.
- colechristensen 9y agoThe mass that's converted to energy in both chemical and nuclear reactions comes from differences in bond energies. Nuclear chemistry is about the bonds between subatomic particles, ordinary chemistry is about the bonds between atoms. Mass-energy conversion isn't a special thing, it's universal. All energy has mass. When energy moves, mass moves, always.
- andrewla 9y agoI'm reasonably certain that this is not correct; this was a viewpoint held fairly briefly in the post-Einsteinian physics community, but abandoned because of a lack of evidence. For the purposes of general relativity, stress-energy is the mass/energy hybrid quantity, but the equivalence is not literal in the sense that in a given inertial reference frame momentum does not attach to energy, but only to mass.
- orblivion 9y agoI've heard of this as well. However, I assume this means that mass turns into kinetic energy specifically, right? And potential energy actually increases with mass? (This isn't something I've heard, it's just the only way I can make sense of things.)
- smsm42 9y agoConverting mass to energy does not violate conservation of mass. But if anybody on the planet managed to convert a pound of mass into energy, we'd hear about it pretty quickly - it's roughly as much energy as a Castle Bravo thermonuclear weapon released. But chemical reactions of course do not involve any significant change of mass, too low energy levels.