How do you prepare potassium manganate from pyrolusite ore?

Question

Statement-I : Consider the following pairs of ions $(\text{Sc}^{3+}, \text{Ti}^{3+}), (\text{Ti}^{4+}, \text{Ni}^{2+}), (\text{Cu}^{2+}, \text{Zn}^{2+})$ and $(\text{Cr}^{3+}, \text{Mn}^{3+})$. Out of these pairs three pairs consist of ions that are both coloured :
Statement-II : Among the lanthanide ions $\text{Eu}^{2+}$, $\text{Gd}^{3+}$, $\text{Ce}^{4+}$ and $\text{Tb}^{4+}$, the ion $\text{Tb}^{4+}$ is the strongest reducing agent.
Choose the correct option.

Answer 1

Reaction of MnO$_2$ (pyrolusite) with KOH and O$_2$:
2MnO$_2$ + 4KOH + O$_2$ → 2K$_2$MnO$_4$ + 2H$_2$O.

How do you prepare potassium manganate from pyrolusite ore?

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Solution and Explanation

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