What Is Dipotassium Manganate?
Dipotassium manganate, with the chemical formula K2MnO4, is an inorganic compound distinct from potassium permanganate (KMnO4). It serves as an intermediate in the synthesis of potassium permanganate and shares similarities with other manganates like barium manganate and sodium manganate.
Uses of Dipotassium Manganate
Primarily used in the industrial production of potassium permanganate, dipotassium manganate undergoes disproportionation in mildly basic aqueous solutions to produce permanganate ions and manganese dioxide. It exhibits unique properties as an oxidizer and changes color based on the pH of the solution, appearing reddish-purple in acidic conditions and dark green in strongly basic conditions.
Properties of Dipotassium Manganate
This compound is a dark green powder at room temperature, with a molecular weight of 197.132, a melting point of 190°C, a density of 2.78 g/mL, and an acid dissociation constant (pKa) of 7.1.
Types of Dipotassium Manganate
Available mainly for research and industrial applications, dipotassium manganate is sold in quantities suitable for laboratory use and as an inorganic salt material. Its most common application is as an oxidizing agent and a synthetic intermediate for potassium permanganate production.
Other Information on Dipotassium Manganate
1. Synthesis of Dipotassium Manganate
Synthesized from manganese oxide (IV) ore (pyrolusite) by melting with potassium hydroxide, or through industrial oxidation processes involving molten potassium hydroxide and manganese dioxide. Laboratory synthesis may involve heating a mixture of concentrated potassium hydroxide solution and permanganate, with other methods including reduction of potassium permanganate with potassium iodide.
2. Chemical Reaction of Dipotassium Manganate
Dissolution in non-strongly basic aqueous solutions leads to disproportionation, producing permanganate ions and manganese dioxide. The reaction mechanism is complex, involving protonation and intermediate manganese (V) species.
3. Toxicological and Regulatory Information
As an oxidizing agent, dipotassium manganate poses fire hazards and can cause skin, eye, and respiratory irritations. It reacts with reducing agents and some metals, necessitating careful handling. It is regulated under various safety and environmental laws, highlighting the need for compliance in handling and storage.