For many of us, chemistry wasn't exactly a riveting subject in school. After all, knowing everything about covalent bonds, stoichiometry, and endothermic reactions probably isn't a necessity during your daily routine. However, a basic understanding of chemistry and chemical reactions can be helpful in survival situations. Don't worry, you won't need to whip out your lab coat and Erlenmeyer flask this time.
WARNING: This chemical is highly corrosive and burns violently, so be careful when handling and storing it. Follow all safety precautions and only use it at your own risk.
Potassium permanganate, or KMnO4, is one chemical which has many survival applications. This purplish-black crystalline powder can be found in bulk at pet stores, pool supply shops, and hardware stores. It doesn't cost much, and a tiny amount goes a long way.
In powdered form, potassium permanganate is an effective fire-starting tool. You just need to add a few drops of glycerin (from a drug store) or ethylene glycol (found in automotive antifreeze and some brake fluids) and the powder will energetically burst into a white-hot flame:
The powdered form of this chemical will also work as a preservative for fruit. One study showed that by placing bananas in a sealed bag with KMnO4, the shelf life of this fruit was extended by two weeks. While interesting, this use is a little obscure — but the chemical has many other survival-oriented functions.
Mixing just a few small crystals of potassium permanganate into a glass of water creates a bright pink solution. This may work as an improvised water purifier if no other options are available, though the CDC does not recommend it “for primary water disinfection at low doses in the field”. We'd agree with the CDC that carrying a purpose-built water filter or purifier is always the best option, but KMnO4 might work in a pinch.
Adding more KMnO4 to water creates a darker purple solution, which can be used as an antiseptic for wounds or sores. The World Health Organization includes it on its list of Essential Medicines, and recommends diluting it in a 1:10,000 ratio. Stronger solutions fight fungal infections such as athlete's foot, but be careful not to go overboard — excessively-concentrated solutions can burn your skin.
Finally, a concentrated solution will stain items purple, and you can use this to your advantage. Strips of stained cloth or splashes of purple liquid in snow could be used to signal for rescue, since this unnaturally-vibrant color will stand out against a natural backdrop.