Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Chemistry - Volumetric Analysis I can't do this

  1. Oct 8, 2006 #1
    How do I find x in FeC2O4.xH2O. I am told that this is a hydrated salt of 1.75g and was dissolved in acid and made up to 250ml. A 25mL sample of this solution required 29.15mL of standardised 0.0200mol/L KMnO4 solution for complete oxidation.

    I worked out n(MnO4-) = cv = 5.83 x 10^-4 moles
    and n(C2O4^2-) = 1.4575 x 10^-3 moles
    and c(C2O4^2-) = n/v = 0.0583 molL-1
    I just don't know how to find x
  2. jcsd
  3. Oct 9, 2006 #2


    User Avatar
    Science Advisor
    Homework Helper

    How would you know of the concentration of the C2O4 anion already? You need to employ the stoichiometric equation for the pertinent reaction and then deduce things from there with the mole value you have for the titrant KMnO4.
  4. Oct 9, 2006 #3


    User Avatar

    Staff: Mentor

    You know number of moles in 25 mL (you have calculated it correctly, BTW), calculate number of moles in 250 mL. Now, number of moles is mass/molar mass - you know mass, you know number of moles, you can calculate molar mass of hydrate. Molar mass is all you need to find x.
  5. Oct 9, 2006 #4
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook