Question

What is the formula, molar mass, and colour of Potassium Permanganate ?

Answer 1

To solve the given problem, we should have the knowledge about Potassium Permanganate, and how to calculate the molar mass of a compound.
Potassium Permanganate is an inorganic compound made from pyrolusite ore. Pyrolusite ore is $MnO_2$ which is brown in colour. It is reacted with Potassium hydroxide to form Potassium permanganate. Potassium Permanganate is an oxidising agent in all mediums .
Molar mass of a compound is calculated by adding the standard atomic mass and multiplying it with their number of atoms.

Complete step by step solution:
Step-1 :
Potassium permanganate is prepared by the disproportionation of potassium manganate in acidic medium.Potassium permanganate is purple in colour and has a formula of $KMnO_4$. The potassium manganate formed is green in colour.
Step-2 :
The molecular formula of Potassium permanganate is $KMnO_4$ . The molar mass of $KMnO_4$ can be calculated as ( Atomic mass of $K$ ) $+$ (Atomic mass of $Mn$) $+$ $4 \times$ (Atomic mass of $O$).
$= 158 g mol^ { -1 }$.

Note:
The preparation and colour and formula for some selective compounds should be remembered. The molar mass can be achieved later.
Chemical formula for Potassium manganate is $K_2MnO_4$ and molar mass is $197 g mol^ { -1 }$. Because of the action of heat, Potassium manganate gets converted to potassium permanganate along with $MnO_2$ and $O_2$.