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
Step 1: Measurements
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.
Step 2: Dissolving the Salt
Pour the water into a pot or pan and bring the water to a boil on a hot plate. When the H2O starts to boil, lower the hot plate’s temperature and empty the stump remover into the pot.
After that, stir the mixture with a spoon or paint stick, preferably with a paint stick, until the stump remover has completely dissolved.
Continue to heat and not boil the solution as you stir it for a few minutes. Add a little more water to the solution if you notice that plenty of the H2O has evaporated. The amount of water is not critical however; you do not want too much or too little water in your solution.