UnDeadDad,
Welcome to the forum, a great place to learn,
Well here is a great experiment to show your daughters, the first part of this do without their help, as the fumes of nitric acid (NOx gas) are very dangerous.
collect your silver scrap (HVAC is a good place, silver solder, contractors, and switches), dissolve the silver in nitric acid, (actually for this to be better for the girls education the more pure silver is better because the solution will be a clear silver nitrate looking like water, so buying a little pure silver would be more beneficial to you and your daughters education, dissolve the silver in diluted nitric acid (for each gram of silver use 2.8ml of 70% nitric acid and 3ml water, adding a little 3% hydrogen peroxide will help keep fumes down some) after reaction stops heat the solution to dissolve more silver, filter the solution, do this part without the girls as the NOx gas fumes are dangerous, outside and do not breath the fumes evolved.
once you have the silver nitrate solution (clear if only silver), (already green to blue with copper if your silver was impure), the best again would be the clear solution to see the reactions more clearly.
Separate off a small volume of the silver chloride, about 20ml is enough here, now show this to the girls (if pure it looks like water), now fill another small 20ml glass with water, show them this, these two will look the same, now let the girls have the salt shaker full of table salt (NaCL) sodium chloride, have them add some salt to the water, and see it dissolve ask them if they see the metal sodium in the solution (clear sodium chloride and water solution), well the sodium metal is dissolved in the water, now have the saturate the water with salt until no more salt dissolves, explain the saturated solution and how heating would dissolve more salt and cooling would precipitate more salt.
now have them look at the silver chloride solution (clear is best) (blue if copper involved), ask them if they see the silver, now mix the clear NaCl salt water, and the clear silver chloride, then notice a fluffy white powder of silver chloride AgCl form stir and let it sit, explain that the sodium metal changed places with the sodium metal, the silver in solution as the white powder is now silver chloride which is insoluble, and the sodium is now a sodium nitrate solution soluble in water, the silver chloride will need conversion before we get it back to the metal state with melting (this will be such a small volume at this time just save it in a jar under a layer of water until you get more.
Silver nitrate mixed with sodium chloride gives silver chloride and sodium nitrate.
AgNO3 + NaCl -–> AgCl + NaNO3
Now move on to the larger volume of silver nitrate solution, again ask the girls if they see the silver in this clear solution, get a clean piece of copper (buss bar, plumbing pipe cut and flattened to a sheet, or wire), hang it into solution after a little bit you will see a gray powder forming on the copper, shake it off into solution and stir solution with the copper, continue this until no more cement forms, in this reaction the clear silver nitrate solution will begin to turn blue (copper ions going into solution),(if you had a more pure clear silver solution to begin with, if not you may not see this if solution already had copper in solution to begin with) the copper is replacing the silver in solution, this silver is ions of silver atoms the nitric acid we dissolved the silver in took electrons from our silver and made a clear solution of silver nitrate with atoms of silver missing electrons, making the metal invisible in solution as silver ions, the silver as a nitrate is oxidized (meaning missing electrons), the copper metal has all of its electrons, but when it was put into the silver nitrate solution id being a more reactive metals (study reactivity series of metals), the copper gave up its electrons to the silver, the silver was reduced (gain of electrons) back to metal, the copper now missing electrons becomes a dissolved ion in solution as copper nitrate salts,
Copper (Cu) metal in a solution of silver nitrate, gives copper nitrate solution and silver metal.
AgNO3 + Cu --> CuNO3 + Ag
Decant the copper nitrate solution to another jar and rinse the cemented silver with water add wash to the copper nitrate solution, dry and melt the silver back to a shiny little button of silver and let the girls hold the silver.
Who knows you may just inspire them to want to learn more chemistry, or collect more silver to have fun with.
