Question

Is ${\mathrm{MnO}}_2$ soluble in water?

Answer 1

Explanation:

Manganese dioxide(${\mathrm{MnO}}_2$) is a black or brown solid that occurs naturally as pyrolusite.

1. Dissolved oxygen oxidizes iron and manganese salts to insoluble salts.
2. Thus manganese dioxide is insoluble in water, Because manganese dioxide has the lowest oxidation state, it would be a parent compound, Thus manganese dioxide is mildly acidic and moderately basic.
3. Thus manganese dioxide is amphoteric in nature.
4. Manganese dioxide readily dissolves in acids.
5. Manganese dioxide is not only soluble in acids but also soluble in ammonium chloride and insoluble in water. Manganese tetroxide is another manganese derivative that is insoluble in water but soluble in $\mathrm{HCl}$.
6. The insoluble nature of manganese dioxide in water is due to dissolved oxygen.

Hence, ${\mathrm{MnO}}_2$ is soluble in water.