dkw@homxb.UUCP (D.WOMBOUGH) (01/24/86)
Can anyone help me with the following problem. I am not really into physics so I can't figure this out I need to know how to calculate the number electrons in a solid copper sphere 10cm in diameter. Thanks Dennis Wombough
gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) (01/26/86)
> I am not really into physics so I can't figure this out > I need to know how to calculate the number electrons in > a solid copper sphere 10cm in diameter. This seems to be a strange "need" you have. Assuming you really want the total number of electrons and not just the number of "free" (conduction) electrons: Volume of sphere = 4/3 Pi r^3, where r = 5cm, => 523.6 cc Density of copper at S.T.P. = 8.9 g/cc Mass of sphere = density * volume => 4660 g Atomic weight of copper = 63.54 g/mole Moles in sphere = mass / at.wt. => 73.3 moles Avogadro's number = 6.02 * 10^23 atoms/mole # atoms in sphere = moles * Avogadro => 4.4 * 10^25 atoms # electrons per atom = atomic number = 29 # electrons in sphere = # atoms * (electrons/atom) => 1.3 * 10^27 electrons So tell us, what good is this information?
rab@well.UUCP (Bob Bickford) (01/27/86)
In article <1165@homxb.UUCP>, dkw@homxb.UUCP (D.WOMBOUGH) writes: > Can anyone help me with the following problem. > I am not really into physics so I can't figure this out > I need to know how to calculate the number electrons in > a solid copper sphere 10cm in diameter. > > Thanks > Dennis Wombough Understand this is just off the top of my head..... First, look up the density of copper, and use that to calculate the mass of the sphere in question. Next, look up the mass of a typical copper atom, divide that into the above result to give number of atoms in the sphere in question. Last, multiply by the atomic number of copper, to give the number of protons in the sphere in question. Assuming no net charge, this will also be the number of electrons in the sphere. Robert Bickford (rab@well.uucp) ================================================ | I doubt if these are even my own opinions. | ================================================
tim@ism780c.UUCP (Tim Smith) (01/28/86)
> Last, multiply by the atomic number of copper, to give the number >of protons in the sphere in question. Assuming no net charge, this >will also be the number of electrons in the sphere. > If the sphere is negatively charged, you still get the right answer, because copper is a conducter, so the extra electrons end up on the surface instead of _in_ the sphere. -- Tim Smith sdcrdcf!ism780c!tim || ima!ism780!tim || ihnp4!cithep!tim