Question

(B) Determination of Oxalate by Titration (Manganometry) Banometry is a type of redox titration based on the following reaction: (MnO4 + 5e + 8H → Mn + 4 HO )x2 (C204 → 2 CO2 + 2 - )x5 2 MnO. + 16 H + 5 CO 10 CO2 + 2 Mn? + 8 H20 Pre-lab Questions - to be answered before you start oxalate determination: 1) Why do you need to acidify the reaction? 2) What would happen if not enough acid is added? 3) How many grams of KMnO do you need to prepare 500 mL of 0.02 M solution? 4) How do you determine the concentration of the KMnO4 solution? - Show your calculations 5) What is the theoretical w% of oxalate in your product? Calculate w% of CO2-for both, anhydride K[Fe(C,04)) and for trihydrate Ks[Fe(C204)a) .3H20. 6) Show your calculation to determine w% by manganometry. Standardization

Answer 1

4) For the determination of concentration, we generally use normality. So we will calculate normality of MnO₄^.

(1) Ino +56 +8HT MORT + 4H2017 '+4420] x2 til Lezen 2002 426 -]+5 2 Mod + 16Ht + 5.204 10202 1) From egn + 16H+ + 54042- joco, +2m2 +840 of for the egn money reduction we can see to maat we need 8HT for each mnou so medim should be sofficently This acidic. aeddity des maintained by adding cone-Broge cone H So. 3) from anti) - Dosna [mm 2T) Emnen maar - Eminema21 Egerne - E geleg u e Turjs [ mnoy [mm] Lgs 8 log [monog ] = Et oosol Lg [v+]8 -0.0591 = ET E ZE ° -0.0591 PA - 0.0591 [mar] ug [mnog] e on reduction potential from from the above on, reduction potential fron depends on pw. If ph increases potential Then it can no longer oxidise 2012- so pH should be sufficently lowered mnen-/m 27 decreases to cozi of enough acid. addition

Now for the conversion of MnO₄^. five electrons are involved.

So equivalence weight = Mol. wt. / 5 = 158/5 = 31.6 g

So a 1000ml 1(N) KMnO₄ will contain 31.6g KMnO4

Accordingly we will calculate cocentration of KMnO4