Because of the sensitivity of potassium to water and air, reactions with other elements are possible only in an inert atmosphere such as argon gas using air-free techniques.
Potassium does not react with most hydrocarbons such as mineral oil or kerosene.
It readily dissolves in liquid ammonia, up to 480 g per 1000 g of ammonia at 0 °C.
Depending on the concentration, the ammonia solutions are blue to yellow, and their electrical conductivity is similar to that of liquid metals.
The minerals best suited for dating include biotite, muscovite, metamorphic hornblende, and volcanic feldspar; whole rock samples from volcanic flows and shallow instrusives can also be dated if they are unaltered.
With oxygen it forms potassium peroxide, and with water potassium forms potassium hydroxide.
The reaction of potassium with water is dangerous because of its violent exothermic character and the production of hydrogen gas.
It is found dissolved in sea water (which is 0.04% potassium by weight), and is part of many minerals.
Potassium is chemically very similar to sodium, the previous element in group 1 of the periodic table.
Hydrogen reacts again with atmospheric oxygen, producing water, which reacts with the remaining potassium.