wasser@mosaic.DEC (John A. Wasser) (01/27/86)
> I need to know how to calculate the number electrons in > a solid copper sphere 10cm in diameter. Find the volume of the sphere (in cc) [is it 4/3 pi r^3?] (104.7197cc?). Multiply by the density of the copper (8.93 gm/cc) to get grams (935.1469gm?). Divide by the atomic weight of copper (63.54) to get Moles (14.71745?). Multiply by Avagadro's number (6.02252e23) to get the number of atoms. (88.63614e23?). Multiply by the number of electrons per atom (29) to get electrons (2570.45e23?). So (if I got the folmula for volume of a sphere correct) the number of electrons in an uncharged 10cm sphere of copper is: 2.57045e26 It's easy! -John A. Wasser
lambert@boring.uucp (Lambert Meertens) (01/30/86)
> Find the volume of the sphere (in cc) [is it 4/3 pi r^3?] > (104.7197cc?). > [...] > So (if I got the folmula for volume of a sphere correct) the number > of electrons in an uncharged 10cm sphere of copper is: > 2.57045e26 The formula is correct, but the value computed is not: 104.7197 = 4/3 pi r^2. The final value given should therefore be multiplied by 5, which gives us about the 1.3 * 10^27 electrons reported by gwyn@brl-tgr.UUCP. -- Lambert Meertens ...!{seismo,okstate,garfield,decvax,philabs}!lambert@mcvax.UUCP CWI (Centre for Mathematics and Computer Science), Amsterdam