can someone please explain how magnetic moment  of an ion is calculated?
454087
Use the formula:\n\nmagnetic moment = sqrt(n(n+2)\nwhere n = number of unpaired electrons.\n\nEg Mn has 5 d electrons, therefore, Mn2+ could have a maximum of 3 unpaired electrons. Plugging 3 into the above formula gives:\n sqrt(3(3+2) = sqrt(15) = 3.87 BM.
1131979
OK.  There was a discrepancy in the atomic mass of elements.  We have electrons, which have insignificant mass, and an equal number of protons (to make the atom neutral), but the atomic mass exceeds the sum of the masses of the protons + electrons.  So we hypothesize that there is another particle in the atom which has atomic mass roughly the same as a proton but no charge.\nIt makes sense that this particle is in the nucleus.\nBUT, we can't use magnetic properties to isolate this particle.  And an atom is pretty much indivisible.  So we must actually strip off the electrons AND the protons to isolate neutrons.  That's not easy.
786730
Use the right hand rule, also known as the rule of thumb. If you have a wire (insulated!) with a current flowing through it, grab the wire in your right hand, with your thumb pointing in the direction that the current is flowing. Your fingers will curl around the wire in the direction of the magnetic field.\n\nIf the current alternates (periodically reverse direction) then the magnetic field also alternates. Envision it as a cylindrical zone that has the wire down its axis, and that the cylinder expands and contracts as the current of electrons increases or decreases. \n\nNow, suppose we wrap our wire around a coil form to make a coil. There is also a right hand rule, or rule of thumb, for coils. If you hold the coil (again, use insulated wire!) with your fingers wrapped around it pointing in the direction that the electron current flows, your thumb will point in the direction of the north pole of the coil.\n\nHow does that work? Remember, we are imagining the magnetic field as a cylindrical region around the wire. But the surface of the cylinder is rotating. (We'll stick with current in only one direction for the time being. It's easier to follow.) So think of the flow of the magnetic field as rotating around the wire. \n\nNow, if we wrap the wire into a coil, the rotation of the segements of the magnetic field add up in the same direction. They are working together. This is why the field is stronger inside the coil.\n\nWe should also think of the magnetic field as composed of individual lines of force that repel one another. That is why, when they exit one end of the coil and return to the other, they spread out in space. \n\nWe can see this if we hold a magnet under a sheet of paper or aluminum foil and sprinkle iron filings on top. They cluster most around the poles where the field lines are concentrated-- the field is strongest-- and more thinly around the outside of the magnet, where the field lines spread out, because the field is weaker there. This holds true for any magnet, not just electromagnets.\n\nI hope this is clear enough to help. It is a little tough trying to understand things we can't see.\n\n19 NOV 06, 1816 hrs, GMT.
867785
Dipole moment is a vector quantity. It is the vectorial sum of all the bond moments in the molecule. \n\nIf the molecule is symmetrical and the bond moments are cancelled by each other then the dipole moment is zero.\n\nIn case of SO3, the dipole moment is zero because the molecule is trigonal planar.\n\nWhereas the BrF5 is square pyramidal and hence has some dipole moment. The Flourine present above the square plane causes this dipole moment.
428919
Basically, all atoms contain positive proton particles and negative electron particles. If protons outnumber electrons then the atom has a positive charge. If there are more electrons than protons then it has a negative charge. Usually, positive atoms and negative atoms cluster together effectively cancelling each other out, but in a magnet they don't. You get all the positive atoms at one end and all the negative atoms at the other. The charge causes it to stick to iron, which will eventually becomes magnetised too as it loses or gains electrons form the magnet.
285758
The force that a magnet exerts is proportional to 1/(r^2), where r is the distance of the object from the magnet. \n\nThe force = (1/(4*Pi*e0)*q1*q2)/(r^2)\nwhere q1,q2 are charges and e0 is a the permittivity of free space.
83355
Okay, you know the right hand rule. Good.\nFirst consider the effect of only the e-field: The e-field is pointing in the +x direction. Therefore, the force it exerts on the proton will also be in the +x direction.\nSecond, consider the effect of only the magnetic field: The magnetic field is pointing in the +y direction; therefore, the force it exerts on the proton will be in the -x direction (you use the rule you described to figure this part out). It so happens, that in the first scenario, the force exerted on the proton by the magnetic field exactly balances that exerted by the electric field. Therefore, the movement of the proton is unaffected.\n\nHowever, in the second case, the proton is accelerated through a potential difference of 2V. Therefore, it will be moving faster (think about it: a higher potential difference has greater "potential" to pull the proton.  Also, the equation F = qvB where q is the charge of the proton, v is its velocity, and B is the magnetic field strength, states that the faster the proton is moving, the greater will be the force exerted on it.  So, compared to the first case with only a 1V potential difference, the magnetic field here will exert a greater force on the proton. But, the force exerted by the electric field is unchanged. So, the net force on the proton will be in the -x direction.
502577
A dipole (Greek: di(s) = double and polos = pivot) is a pair of electric charges or magnetic poles of equal magnitude but opposite polarity (opposite electronic charges), separated by some, usually small, distance. Dipoles can be characterized by their dipole moment, a vector quantity with a magnitude equal to the product of the charge or magnetic strength of one of the poles and the distance separating the two poles. The direction of the dipole moment corresponds, for electric dipoles, to the direction from the negative to the positive charge. For magnetic dipoles, the dipole moment points from the magnetic south to the magnetic north pole — confusingly, the "north" and "south" convention for magnetic dipoles is the opposite of that used to describe the Earth's geographic and magnetic poles, so that the Earth's geomagnetic north pole is the south pole of its dipole moment. Because of the absence of magnetic monopoles, magnetic dipoles are actually created by current loops or by quantum-mechanical spin.\n\nSince the direction of an electric field is defined as the direction of the force on a positive charge, electric field lines point away from a positive charge and toward a negative charge.\n\nWhen placed in an electric or magnetic field, equal but opposite forces arise on each side of the dipole creating a torque τ:\n\n \nfor an electric dipole moment p (in coulomb-meters), or\nfor a magnetic dipole moment m (in ampere-square meters).\n\nThe resulting torque will tend to align the dipole with the applied field
561926
XeF  + e-  ============> Xe  + F-      E°/V = 3.4 with reference to the standard hydrogen electrode
729557
_NaOH(aq) + _Fe(ClO4)3(aq) => _Fe(OH)3(s) + _NaClO4(aq)\n\n3  NaOH(aq) + 1  Fe(ClO4)3(aq) => 1  Fe(OH)3(s) + 3  NaClO4(aq)\nThe coefficients of one could be excluded but I put one which is also equivalent.\n\n_((NH4)2)SO4(aq) + _Pb(NO3)2(aq) => _PbSO4(s) + _NH4NO3(aq)\n\n1  ((NH4)2)SO4(aq) + 1  Pb(NO3)2(aq) => 1  PbSO4(s) + 2  NH4NO3(aq)\n\nThese are only the balanced equations.\n\nThe following is the ionic equations:\n(Na)+ (aq) + (OH)- (aq) + (Fe)3+ (aq) + (ClO4)- (aq) => Fe(OH)3(s) + (Na)+ (aq) + (ClO4)- (aq)\nand\n(NH4)+ (aq) + (SO4)2- (aq) + (Pb)2+ (aq) + (NO3)- (aq) => PbSO4(s) + (NH4)+ (aq) + (NO3)- (aq)\n\nThe ionic equations are already balanced.  It is simply the breaking down of the equations into ions.  The solid remains intact while the compounds in aqueous solution become ions.\n\nThe + and - signs are the charge of the ions.  I can't find any other way to write them so I separated the compound with parentheses.  Sorry if it's confusing.\n\nThe net ionic equations are "simplified" ionic equations.  Basically, the things that are repeated on both sides get crossed off.  What is remaining is simply the net ionic equation.\n\n(OH)- (aq) + (Fe)3+ (aq) => Fe(OH)3(s)\nand\n(SO4)2- (aq) + (Pb)2+ (aq) => PbSO4(s)
921926
mg + ion\no -ion\nk +ion\ns -ion\nwhen they are 'added' together (MgO and K^2S) the charges are balanced, that means that the net charge is 0.
746933
You could use the Van't Hoff equations to calculate this.\nOP = i * c * RT\nwhere i is the number of ions per particle and the membrane will be retaining the ions.\n\nBecause RT will be constant for all of them, you only need to compare the product i *c for each solution.  So OP/RT for the solutions above will be.\n\nNa2S ===> 0.30 * 3 = 0.9\nMgCl2 ===> 0.2 * 3 = 0.6\nEtOH ===> 0.50 * 1 = 0.5\nKCl ===> 0.50 * 2 = 1.0\nso the answer is KCl, Na2S, MgCl2, EtOH.
691296
use that at equilibrium : n.p = ni^2\nand from charge neutrality: \n\nn + NA = p + ND
798559
positive ions are formed by removing electrons from the atoms and hence the ionic radius for positive ion is always less than that of atomic radius
909738
It will rotate about the center of mass O at d/2\ncalculate the moment or inertia about  O, include both mass and both rods. see link for formulas if you don't know how\nhttp://en.wikipedia.org/wiki/Moment_of_inertia\nThe formula for KE is also there
941802
In order to do this, you need to realize what the balanced equation is really saying, and what relation that has to mass.  Your equation says that for every 4 iron atoms that react with 3 diatomic oxygen molecules, you'll produce 2 iron (III) oxide molecules.  Molecules are great and all, but that doesn't help you when you're trying to figure things out in terms of grams.  That's where Avogadro's number and the concept of the mole come into play.\n\nOn the periodic table, you'll notice that there are two numbers for each element:  the atomic number, which is the number of protons in an atom of the element; and the atomic weight (or mass), which is the total weight, in grams, of one mole (6.022 X 10^23 atoms) of that element.  (The atomic weight is also roughly equal to the total number of protons and neutrons in the most common isotope of the element.)\n\nIn order to figure out how much product you'll produce, you need to figure out how many moles of Fe you have, then work out the proportions.  Start by figuring the molar mass of each molecule in the reaction:\nFe = 55.845\nO2 = 2(15.9994) = 31.9988\nFe2O3 = 2(55.945) + 3(15.9994) = 159.8882\n\nNow figure out how many moles of Fe you have:\n4086 g/55.845 g/mol = 73.167 mol\n73.167 mol/4 mol Fe\n\nNow figure out how many moles of Fe2O3 you produce:\n(73.167/4) X 2 = 36.584 mol Fe2O3\n\nMultiply this by the molar mass of Fe2O3 to get the mass of the product:\n36.584(159.8882) = 5849.350 g Fe2O3\n\nb) Do the same thing you did in a), just substitute O2 for Fe2O3:\n(73.167/4) X 3 = 54.875 mol O2\n54.875 x 31.9988 = 1755.942 g O2
882885
Hysteresis is the slight difference between how something reacts going one way compared to how it acts going the other way.\n\nA typical example is a magnet. As it magnetizes, it passes through the origin (the point at which 0 electric field intensity equals 0 magnetic field intensity). This is because the initial charge of magnetism is going into an "empty" container, so to speak.\n\nHowever, when the magnet is demagnetized (or the field is flipped to the opposite polarity), there will be a small amount of "residual" magnetism from the first charging that will tend to "fight" against the reversal. What this really means is that the reverse polarity charge does not follow the exact same path ... and does not pass through the initial origin at all.\n\nYou could look at this as filling and then emptying a glass with water - the first time you fill it, the glass started out completely dry ... which meant you could put X many molecules of water into it. Then you dump it out ... but a few molecules remain adhered to the glass surface (this would be the residual). The next time it's filled, you add as much as the first time (less the residual).\n\nWhen you empty it again, it leaves a couple of molecules attached. Not necessarily the same ones as the first time, but approximately the same amount. Hence there is now a hysteresis effect occurring when you fill/empty the glass.