Page 40 - Curriculum Visions Dynamic Book

Red phosphorus
When white phosphorus is heated in the absence of air it changes to red phosphorus. This is much less reactive than white phosphorus and only bursts into flame when it is heated by friction. The main use of red phosphorus is for safety match heads, tracer bullets, smoke screens and skywriting.
Matches
Matches consist of an incendiary (fire- making) device and a source of fuel, the wood of the match stick. The first matches were tipped with sulphur but these needed a spark from a flint in a tinder box to
light them.
Friction matches – those that ignite
simply by being rubbed against a rough surface – were invented in the 1830s. The “strike anywhere” matches were tipped with mixtures that included the incendiary chemical white phosphorus that could ignite by spontaneous combustion.
These are the matches that will ignite when scraped against any surface. However, many accidents were caused by accidental scraping, so today a more stable (and nonpoisonous) chemical containing phosphorus is used.
Safety matches use red phosphorus
(on the side of the match box, not in the match head) for ignition. The match head contains potassium chlorate (a source of oxygen). When the match is struck, the head scrapes across the phosphorus on the match box side, causing a small amount of red phosphorus to heat up and come into contact with a source of oxygen. It then reacts and ignites, in turn causing the match head to begin to burn for long enough to catch the wood of the stick alight.
40
40