the volume of 0. 5M KMnO4 solution which can oxidise 20 ml of 0.2 M Mohr salt solution in acidic medium is 1) 1.6 ml 2) 3.2 ml 3) 4.8ml 4) 5 ml
To find the answer, we need to understand the balanced chemical equation for the reaction between KMnO4 (Potassium permanganate) and Mohr salt (Fe(NH4)2(SO4)2·6H2O) in acidic medium.
The balanced chemical equation for the reaction is:
5Fe(NH4)2(SO4)2·6H2O + 2KMnO4 + 8H2SO4 -> 5Fe2(SO4)3 + 2MnSO4 + K2SO4 + 8(NH4)2SO4 + 16H2O.
We can see from the balanced equation that 5 moles of Mohr salt (Fe(NH4)2(SO4)2·6H2O) react with 2 moles of KMnO4.
Therefore, the number of moles of Mohr salt in 20 ml of 0.2 M solution can be calculated as follows:
Moles of Mohr salt = (Volume of solution in liters) x (Molarity of solution)
= (20 ml) x (0.2 M) x (1 L / 1000 ml)
= 0.004 moles.
From the balanced equation, we can see that 5 moles of Mohr salt react with 2 moles of KMnO4.
Therefore, the number of moles of KMnO4 required to react with 0.004 moles of Mohr salt can be calculated as follows:
Moles of KMnO4 = (Moles of Mohr salt) x (Ratio of KMnO4 to Mohr salt)
= 0.004 moles x (2 moles / 5 moles)
= 0.0016 moles.
Now, we need to determine the volume of 0.5 M KMnO4 solution required to contain 0.0016 moles of KMnO4.
The formula to calculate volume is as follows:
Volume of solution = (Moles of solute) / (Molarity of solution)
Volume of KMnO4 solution = (0.0016 moles) / (0.5 M)
= 0.0032 L
= 3.2 ml.
Therefore, the volume of 0.5 M KMnO4 solution required to oxidize 20 ml of 0.2 M Mohr salt solution in acidic medium is 3.2 ml.
So the correct answer is option 2) 3.2 ml.