Copper has better corrosion resistance, is stable in dry air, and does not react with dilute hydrochloric acid or dilute sulfuric acid. But in humid air, the surface of copper can form a layer of green Basic Copper Sulphate (aqua green). Cu2 (OH) 2CO3. Heating patina ":

  1. Take a small amount of "patina" in a test tube (using a medicine spoon or paper trough).
  2. Ignite the alcohol lamp (introduction to alcohol lamp, ignition method-use matches),
  3. Clamp the test tube with a test tube clamp (set it from the bottom to the top, and clamp it 1/3 away from the test tube mouth).

4, heating (preheating at the bottom of the test tube, then concentrated heating), let students observe the phenomenon.