A) ...............................................1st...........................

Question

A)

...............................................1st...............................2nd....................3rd

1. Mass of FAS added............0.5189g.....................0.5006g..............0.5742g

2. Molar Mass of FAS Fe(NH4)2(SO4)26H2O................392.13g

3.MolesofFASadded..............1.323x10^-2mol......1.277x10^-2mol........1.464x10^-2mol

4. Final buret reading.............27.03ml...................26.99ml...................25.5ml

5. Volume of MnO4-...............27.03ml...................26.99ml...................25.5ml

6. Molar ratio MnO4-/FAS......................................1mol MnO4/5 mol FaS

7. Moles of MnO4- ...............2.6447X10^-4mol....2.554x10-4mol.......2.928x10^-4mol

8. Molarity of Solution ..........0.00979M................0.00946M................0.0115M

9. Average Experimental Molarity of MnO4- solution...............0.01025M

10. Report Molerity of KMnO4 solution.....................................??????

11. Percent error between the calculated and the experimental determination of the molarity of the MnO4- solution?????

12. Show the calculations for the determination of the molarity of the permanganate solution.

B)

Unknown identification letter or number...............................??????

Concentration of your KMnO4 solution (Part A)...................??????

Volume of the unknown iron solution used...........................25ml

Titration with MnO4-..................... 1st.........................2nd.........................3rd

Volume of MnO4-..........................3.50ml...................3.5ml.......................3.5ml

Moles of MnO4-............................2.647x10^-4mol.....2.554x10^-4mol......2.928x10^-4mol

Average number of moles of MnO4-..........................................?

Molar ratio between MnO4- and Fe(II).......................................?

Moles of Fe (II) in unknown solution..........................................?

Concentration of unknown Fe (II) solution.................................?

Show how the molarity of the Fe (II) solution was determined...?

Explanation / Answer

10 . molarity of KMNO4 solution = calculated value of molarity during preparation of KMnO4 solution

11. To calculate the error value of calculated molarity is required.

% error = (calculated molarity - experimental molarity/ calculated molarity ) * 100

12. Concentration of your KMnO4 solution (Part A) = 0.01025 M

Volume of the unknown iron solution used = 25ml

Average number of moles of MnO4-

= 2.647x10^-4 + 2.554x10^-4 + 2.928x10^-4

= 2.71*10^-4

Molar ratio between MnO4- and Fe(II) = 1mol MnO4-/5 mol Fe2+   [The reaction is : 8H+ + 5Fe2+ + MnO4- --> 5Fe3+ + Mn2+ + 4H2O]

Moles of Fe (II) in unknown solution = 5* 2.71*10^-4

= 1.35*10-3 M

Concentration of unknown Fe (II) solution

= 1.35*10-3 moles * 1000/25 mL

= 0.054 M

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