Challenge: How do you start a fire?

There are various ways to start a fire. Here is a small list of the possibilities:

• Potassium permanganate and glycerol: When potassium permanganate (a strong oxidising agent) comes into contact with glycerol (an organic compound that acts as a reducing agent), an exothermic reaction can occur that takes place very quickly and releases a lot of heat. This reaction can lead to sudden ignition, as the oxidation of the glycerine by the potassium permanganate generates a high temperature. Caution: The mixture can lead to an uncontrolled fire. It is therefore very important to be extremely careful when working with these substances and to use a fireproof support (e.g. made of stone).
• Chewing gum paper and battery: The aluminium-coated paper must be cut with scissors, folded in half and cut into a triangle - but be careful! - When unfolded, both triangles should still have a connection of +/- 1 mm. Now connect both poles of the AA battery to the aluminium-coated side. As a strong current is now flowing, which is also highly concentrated at the narrowed point, this is where it gets hottest. So hot that the paper starts to glow. If you are skilful, you can light the cotton at this point.
• Steel wool and battery: When steel wool (which consists of thin iron fibres) comes into contact with the poles of a battery, especially a strong battery (such as a 9V battery), it ignites. Here is the process in detail: first there is a short circuit through contact; when the steel wool touches both poles of the 9 V battery, a closed circuit is created. As the fibres of the steel wool are very thin, they have a high electrical resistance. As a result, the fibres heat up strongly. The glowing iron immediately reacts with the oxygen in the air. This reaction is an oxidation and takes place very quickly, so that it looks as if the steel wool is ‘burning’. This produces iron oxide (Fe₂O₃ or Fe₃O₄) - i.e. rust. A solid iron wire or a metal block, on the other hand, would also conduct the current, but would have a much lower resistance and would not heat up as much. In addition, the surface area for the reaction with oxygen would be much smaller. Caution: Risk of injury: reaction produces sparks. There is also a risk of skin burns in the event of direct contact. Improper handling (e.g. by overheating the battery or creating too strong a short circuit) can lead to an explosion or the release of toxic substances.

• Two other well-known methods are friction between soft wood and hard wood, e.g. applying the wooden dowel to the notched area on the wood using the cordless drill; and the use of fire steel in combination with metal (e.g. from scissors).

With all these experiments, safety measures must not be neglected! (gloves, safety glasses). Always have a suitable fire extinguisher or water ready in case of fire. A fireproof surface (e.g. made of stone) is also essential.