K2MnO4n

K2MnO4n denotes a family of hydrated potassium manganate solids, where n is the number of water molecules per formula unit. It is not a single fixed compound but a set of hydrates that crystallize from aqueous solutions of potassium manganate under different conditions. The manganate ion is MnO4^2− with manganese in the +6 oxidation state; in solid form, potassium ions balance the charge, and water molecules may be incorporated into the crystal lattice.

In solution, manganate(VI) species are typically green and exist in basic environments. The solid hydrates arise when crystallization captures water molecules in the lattice. The exact hydration level (n) can vary with temperature, concentration, and water activity, producing different crystalline hydrates of K2MnO4.

K2MnO4n is generally less stable than its permanganate counterpart under many conditions. In aqueous solution and upon heating or in the presence of acids, manganate tends to disproportionate to manganese dioxide (MnO2) and permanganate (MnO4−), a process that limits practical use. In strongly basic media, manganate can act as a mild oxidizing agent, but its chemistry is often overshadowed by permanganate reactivity.

Applications of manganates are primarily in academic contexts to study redox behavior, disproportionation reactions, and as precursors to permanganates. Safety considerations follow those for oxidizing salts: K2MnO4n can be a strong oxidizer and may react vigorously with organic materials or reducing agents; handle with appropriate precautions, and avoid contact with acids and heat. Desiccated or properly stored samples are typically used to minimize hydrolysis and unwanted reactions.