12.18 g of FeSO4•XH2O crystals were dissolved
in dilute sulphuric acid and volume made up to 500 mL. 25.0
mL portion of this solution required 43.85 mL 0.01M KMnO4
solution to reach the end point. Determine x.
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Here the crystals are dissolved in dilute sulfuric acid
Titration
Potassium manganate + Iron(II) Sulfate
The equation should be
10FeSO4 + 2KMnO4 + 8H2SO4 -> 5Fe2(SO4)3 + K2SO4 + 2MnSO4 + 8H2O
- You need the number of moles of FeSO4xnH2O, which is equal to the number of moles of FeSO4.
- You need to determine the volume of KMnO4 needed to react with the solution (the equivalence point is reached when the purple color won't disappear anymore, as there are no Fe2+ ions left to oxidize).
- Now you can calculate the number of moles of KMnO4 and then using the equation you can find out the amount of FeSO4 in the solution.
- As you have diluted the original solution you have to do some additional calculations to determine the amount of Fe2+ ions you started with.
The main formula to use is concentration (mole/dm3) = number of moles (mole) / volume (dm3).
H2SO4 is needed because acidic environment is needed for the reaction to take place.
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