Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    3
    ReputationRep:
    a) Combine the two half-equations (given in the introduction) to give the overall redox equation for the reaction that has taken place during the titration.

    MnO4- + 8H+ + 5Fe3+ = 5Fe2+ + Mn2+ + 4H2O

    b) Use your overall equation to determine the ratio of moles of manganate(VII) ions that react with iron(II) ions.

    1: 5

    c) Use the average titre to calculate the moles of manganate(VII) ions which have been used in the titration.
    Average titre was 18.20 cm3
    concentration of manganite ions : 0.0200g
    number of moles = 0.0200 * 18.20/1000 = 3.64 x 10-4

    d) Calculate the amount, in moles, of iron(II) ions in the 25 cm3 sample of iron(II) sulfate.

    3.64 x 10-4 * 5 = 1.82 x 10-3 mol

    e) Calculate the amount, in moles, of iron(II) ions in the 100 cm3 graduated flask at the start of the experiment.
    1.82 x 10-3 x (100/25)= 7.28 x 10-3

    f) Calculate the mass of Fe in the original five iron tablets and hence the mass of Fe in one iron tablet.
    n x mr = m
    7.28 x 10-3 * 55.8 = 0.41g

    0.41g / 5 = 0.08g

    CAN SOMEONE PLEASE CHECK THESE ANSWERS?? THANKYOU XX
    •  Official Rep
    Offline

    15
    ReputationRep:
     Official Rep
    Sorry you've not had any responses about this. Are you sure you've posted in the right place? Here's a link to our subject forum which should help get you more responses if you post there.

    You can also find the Exam Thread list for A-levels here and GCSE here. :dumbells:


    Just quoting in Puddles the Monkey so she can move the thread if needed
    Spoiler:
    Show
    (Original post by Puddles the Monkey)
    x
    Offline

    2
    ReputationRep:
    Without doing the rest of the question (about to go to a meeting...) your first equation looks wrong. the Fe2+ should be on the left hand side of the equation. it should read:

    MnO4- + 8H+ + 5Fe2+ = 5Fe3+ + Mn2+ + 4H2O

    Hope that helps!
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by ajsullivan)
    Without doing the rest of the question (about to go to a meeting...) your first equation looks wrong. the Fe2+ should be on the left hand side of the equation. it should read:

    MnO4- + 8H+ + 5Fe2+ = 5Fe3+ + Mn2+ + 4H2O

    Hope that helps!
    LOL thanks
 
 
 
Poll
Who is your favourite TV detective?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.