Q. How many mL of magnesium permanganate(0.2 M) will be needed to oxidise 30 mL 0.1 M ferric oxalate solution in dil. `H_2SO_4` medium? A) 18 B) 6 C) 9 D) 3

llltkl | College Teacher | (Level 3) Valedictorian

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In dilute acid medium, magnesium permanganate and ferric oxalate undergo a redox reaction to produce CO2 and Manganous salts as per the balanced reaction:

`3Mg(MnO_4)_2+5Fe_2(C_2O_4)_3 + 24H_2SO_4 rarr 3MgSO_4+6MnSO_4+5Fe_2(SO_4)_3+30CO_2+24H_2O`

Here, magnesium permanganate solution acts as the oxidizing agent and ferric oxalate solution, as the reducing agent.

According to the stoichiometry of the reaction,

5 moles of ferric oxalate react with 3 moles of magnesium permanganate.

Therefore, `0.1*30*10^(-3)` moles of ferric oxalate should react with `(3*0.1*30*10^(-3)) /5` i.e. 0.0018 moles of magnesium permanganate.

Number of mililiters of 0.2 MÂ magnesium permanganate solution that contains 0.0018 moles is

`=(0.0018*10^3)/0.2`

=9

Hence correct answer is option C).

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