My wife told me to do potassium because her business’s mascot is a banana character. Now there is a clear distinction between the elemental potassium and the potassium molecules in the banana. Interestingly, there’s more potassium per cup in avocados, kiwis, and guava than there are in bananas. The potassium molecules in these fruits are quite stable so they behave way differently than the ones you find on YouTube blowing up with some water.
Potassium is number 19 on the periodic table of elements and recognized as an alkali metal. It is a silvery and soft metal. It’s really weird, it looks like metal so you don’t think you can cut it, but you can take a knife and cut it like butter. You can also manipulate it with your hands. So why is it so dangerous to handle?
Looking at the NFPA rating, it’s a 3 on health, 3 on flammability, 2 on reactivity and it is water reactive and a pyrophoric. So how does it blow up and generate fire?
When potassium reacts with water it generates potassium hydroxide and hydrogen gas. Potassium is also oxidized by the oxygen in air forming potassium oxides, peroxides and superoxides. Since almost all oxidation reactions are exothermic, the sudden increase in temperature reaches the autoignition temperature of hydrogen thus causing the hydrogen to ignite. The peroxides decompose creating more oxides thus enhancing the flames. The generation of potassium hydroxide makes the solution very caustic which is why its an alkali metal.
Handling
Make sure that you handle potassium in vacuum or in a glove box as presenting it in open air will cause immediate formation of oxides and ignition. Try to work on a microscale to reduce the risk of major explosions or fires.
Fire-Fighting
If a fire were to occur, make sure that you use appropriate fire extinguishers. Potassium fires are class D fires and extinguishers like MET-L-X or ones with sodium chloride should be used. Adding water to extinguish potassium is discouraged.
Storage
Do not store potassium for long periods of time. The generation of superoxides due to container or storage failures can be enhanced thus increasing the risk of explosion. Make sure to submerge the potassium in anhydrous mineral oil to prevent exposures to moisture or air.
PPE
You can handle potassium with nitrile gloves since it will offer good protection against the potassium hydroxide that could form if potassium were to be mixed with water.
Make sure that you wear safety goggles and a flame resistant lab coat. Depending on the scale, a face shield or blast shield is advised.
Waste
Do not throw potassium in the trashcan, landfill or down the drain. It must be disposed of as hazardous waste. Ensure that it is fully submerged in mineral oil and your EHS contact will be able to take it or overpack it at the site of generation.
So, yes, this is why we do not blow up when we consume bananas or avocados with water as it is not the elemental potassium.
Leave a Reply