Song: Battle Without Honor or Humanity by Tomoyasu Hotei
Procedures for purifying chemicals are being invented and re-invented all the time. Purification depends very much on the chemicals that are considered the “contamination”, and their properties compare to the chemical you are trying to purify. The mixture that you are trying to purify will dictate how easy the purification process will be. There are no– "one fit all solutions", and indeed, some chemicals are so hard to purify that the finished purified product will fetch amazing prices.
Recrystallization is a physical method targeting the purification of compounds. This procedure involves dissolving a compound in a hot solvent to form the saturated solution followed by cooling down the solution. The dissolved compound would crystallize from the solution due to the difference in solubility at high and low temperatures. This method is especially effective for potassium nitrate (KNO3) since its solubility in 158g of water is 247g at 100 degrees C, and only 13.3g at 0 degrees C.
Stump remover that contains Saltpeter (KNO3)
Paint stick or spoon
Pot or pan
First, weigh out 247g of stump remover and set it to the side. Now measure 175ml of H2O (which is about 158g in weight). You can multiply these numbers if you would like.