Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: psc on 06/09/2010 16:19:48
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Dear Chris and company,
Please bare with me so you can relate to my question.
I read the following with interest as I have been looking for an answer for this question ever since I saw a program called catalyst on ABC TV and before but I could never satisfy my self that what I thought was correct.
http://www.thenakedscientists.com/forum/index.php?topic=16622 (http://www.thenakedscientists.com/forum/index.php?topic=16622)
No one could give me a clear explanation on the mechanics of it..until now.
to Quote lightarrow...
1. The energy you give to the battery, and its mass as consequence, since the battery stays still, goes in increasing the chemical potential of its compounds; PbO2 for example has a greater chemical potential than PbO or PbSO4. Essentially the chemical potential is related with the electronic potential of the chemical species. Simplifying furthermore, the increase in mass goes in the increase of the electromagnetic fields of the chemical's electrons.
A simple example: you give electromagnetic energy (of the right frequency) to an hydrogen's atom. The atom absorbs a photon and as a consequence its electron jumps up to the first excited level. At this moment the hydrogen atom has not the mass it had before: its mass is increased (almost exactly) of E/c2 where E is the photon's energy.
"Almost exactly" because the atom don't stay exactly still after have absorbed the photon (anyway the difference is very small).
Where does the atom's mass increase has gone? It has gone in the increased electromagnetic field in the space between the nucleus and the atom's outer edge (the excited atom has a different spatial distribution of the electron).
My questions are
1.Referring to "...the increase in mass goes in the increase of the electromagnetic fields of the chemical's electrons." Does Electromagnetic energy have mass? Or (apparent) mass attributed through E=mc²? then is it real mass as we know it? IE, Will the force of gravity increase on the H atom? I have difficulty in grasping the idea? May be a reference or example might help.
2. if a hydrogen atom were to be thrown the mass would increase. In this situation mass would increase by E/C² where E is ½mv² (in flight)is this correct. Where does this mass increase go? into the electromagnetic field? How? We accept that mass increases, I accept that mass increases, but where does the extra mass go. is it distributed equally among protons, (neutron for other elements), electrons...etc?
Stand alone questions.
If I am presented with a mole of what looks like an electron circling a proton and someone asks what is this and I answer
the mass is 1g therefor it is an energy of approx. 9x10^13J would I be called a fool or failed in an exam?
I know it would depend on which exam I suppose, but why, the truth is the truth. Is the answer a mole of hydrogen more truthful then the energy?
If we can say that a mole of H atoms is energy then what is real.
are electrons and protons real? Or wishful thinking? I think they are particles so they are?
Is the rock that I trip over energy or matter? if matter why?
Why is the "particles" that come out in a cyclotron called particles and not energy?
Hope you will be able to answer as clearly as the battery question.
Patrick
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Since we're in the process of digging through the archive and solving previously-unsolved mysteries, who would like to have a go at this one?
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"Can chemical reactions alter the mass of a material?"
Yes, but not enough to measure.
If I put two chemicals in a sealed flask and they react producing some heat then the flask's contents become warm.
But the mass of the flask and it's contents remains the same.
If I leave it to cool down then there's a tiny change in mass. (It's the E=MC^" bit you mentioned).
If I heat something there's a tiny change in mass.
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Can chemical reactions alter the mass of a material?
In the 1700s, when scientists were struggling with a modern concept of chemical elements, the popular theory about burning was that the fire showed release of an element called "phlogiston".
When it was pointed out that metals burned in air gained mass, it was deduced that phlogiston must have negative mass (or, at least, be lighter than air).
All was resolved with the discovery of oxygen in the air; a burning metal reacted with oxygen, and gained mass.
See: https://en.wikipedia.org/wiki/Phlogiston_theory#Challenge_and_demise
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Just to put this perspective a little:
If 2.00 grams of hydrogen and 16.0 grams of oxygen are reacted to form liquid water (very large energy per mass as far as chemical reactions go), about 286 kJ will be released. Using E = mc2 (rearranged to m = Ec–2, we can calculate that about 3.2 nanograms of mass would be lost (0.000000018%).
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Worth pointing out too that a single element can change mass dependant on the bonds it forms amongst itself. Carbon in the form of graphite or diamonds has different structure and different bond strengths dependant on the form and thus a slightly different molar weight. When creating diamonds with pressure the structure changes to bonds with different numbers and strengths, thus altering the mass very very slightly.