Question

What would be the number of moles of $MnO_4^ - $ required to oxidize one mole of ferrous oxalate completely in acidic medium?
A) $7.5$ moles
B) $0.2$ moles
C) $0.6$ moles
D) $0.4$ moles

Answer 1

Hint:As we know that one mole of a substance is the amount of substance divided by the total molecular mass of the substance and permanganate reacts with ferrous oxalate in presence of acidic medium to give manganese ions and ferrous ions and liberates carbon dioxide and water molecules.

Complete answer:
As we know that three permanganate being an oxidising agent reacts with five ferrous oxalate molecules in presence of acidic medium to give three manganese ions and five ferrous ions and liberates ten carbon dioxide and twelve water molecules. We can show this balanced equation as shown below:
$3MnO_4^ - + 5Fe{C_2}{O_4} + 24{H^ + } \to 3M{n^{2 + }} + 5F{e^{3 + }} + 10C{O_2} + 12{H_2}O$

Now using the above equation, we can say that three moles of permanganate reacts with five moles of ferrous oxalate molecules in presence of acidic medium (twenty four moles of hydronium) to give three moles of manganese ions and five moles of ferrous ions and liberates ten moles of carbon dioxide and twelve moles of water molecules.

Now, $3$ moles of $MnO_4^ - $ are required to oxidise $5$ moles of ferrous oxalate.
So, the number of moles of $MnO_4^ - $ required to oxidise $1$ mole of ferrous oxalate will be $\dfrac{3}{5}$ moles which will give us $0.6$ moles.
Therefore we can say that $0.6$ moles are required to oxidise one mole of ferrous oxalate.

Hence the correct answer is option (C).

Note:Remember that permanganate is a strong oxidising agent because manganese is present in its highest oxidation state which is $ + 7$. It is generally purple in colour and stable in an alkaline medium. Thus it is commonly used in quantitative titrations. Ferrous oxalate is generally yellowish orange powder which is made up of water solution of oxalate and ferrous salt but it is poorly soluble in aqueous solution and it is used as a light sensitive element of photographic prints.