When potassium permanganate and heat are placed in a test tube, the solution will react in a few ways. First, the heat will cause the potassium permanganate to break down into its component parts, which are oxygen and manganese dioxide. This reaction will release heat and cause the solution to bubble. Additionally, the manganese dioxide will react with the oxygen to form manganese oxide, which will cause the solution to turn a dark purple color. Finally, the reaction will produce an exothermic reaction, which means it will produce heat.
The overall reaction equation is:
2KMnO₄ + Heat → 2K₂O + 2MnO₂ + Heat