Please show work! Thank you! One of the analyses of the composition of the green
ID: 814725 • Letter: P
Question
Please show work! Thank you!
One of the analyses of the composition of the green oxalato-iron complex requires the redox titration of oxalate against potassium permanganate.
In the preparation of the potassium permanganate solution, what approximate mass of potassium permanganate is required to make 400 mL of a 0.02 M solution?
1) Approximate mass of KMnO4 required = g
Suppose that you weighed out approximately this amount of potassium permanganate and dissolved it in distilled water to make 400 mL of solution.
0.1089 grams of pure dry sodium oxalate was placed in an Erlenmeyer flask and dissolved in 75 mL of 0.75 M sulfuric acid. This acidic solution of sodium oxalate was titrated against the potassium permanganate solution.
The volume of potassium permanganate required to reach the end point was 15.79 mL.
How many moles of sodium oxalate were used in the titration?
2) Moles of sodium oxalate = mol
Calculate the equivalent number of moles of potassium permanganate.
3) Moles of potassium permanganate = mol
Therefore, calculate the molarity of the potassium permanganate solution.
4) Molarity of the potassium permanganate solution = M
Explanation / Answer
mass of KMnO4 required
= volume* molarity* mol.wt KMnO4
= (0.400 L) x (0.02 mol/L KMnO4) x (158.0 g KMnO4/mol)
= 1.26 g KMnO4
***Approximate mass of KMnO4 required = 1.26 g
2)
Moles of sodium oxalate = mass of sodium oxlate / mol.wt of sodium oxlate
= (9.022 x 10^-2 g Na2C2O4) / (134.00 g Na2C2O4/mol) = 0.0006733 mol Na2C2O4
***Moles of sodium oxalate = 0.0006733 mol
3)
2 MnO4{-} + 16 H{+} + 5 C2O4{2-} ? 2 Mn{2+} + 8 H2O + 10 CO2
(0.0006733 Na2C2O4) x (2 mol KMnO4 / 5 mol Na2C2O4) = 0.0002693 mol KMnO4
***Moles of potassium permanganate = 0.0002693 mol
(0.0002693 mol KMnO4) / (0.01262 L) = 0.05335 mol/L KMnO4
***Molarity of the potassium permanganate solution = 0.02156 M