Redox Titration Question!!

Question

What is the concentration of Fe2 (aq) in 15.00mL of sample solution when acidified 0.0200M MnO4-(aq) is used as the titrant and the average titration volume is 14.0mL?

A. 4.71x10-2M

B. 1.92x10-2M

C. 9.33x10-2M

D. 3.79x10-2M

I've done this 3 times and I still get A. but it's WRONG. So can someone tell me what's the correct way of solving this question?

Answer 1

Fe 2+ --------> Fe3+ +e-

8H+ + 5e- + MnO4- ------> Mn2+ + 4H2O

5Fe2+ + 8H+ + MnO4- ---------> 5Fe3+ + Mn2+ + 4H20

If 14.0mL is used then 14*.0200M=.280 mmol MnO4- is used.

At the endpoint of the titration, just the right amount of MnO4- was added to completely use up the Iron...so there was .280x5=1.40 mmol Iron in the solution being titrated. That was in a volume of 15.00mL orignally, so the concentration was 1.40/15.00= .0933   = answer C