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

    3
    ReputationRep:
    So this is the redox equation provided
    5fe2+ + MnO4- + 8H+ --> 5Fe3+ + Mn2+ + 4H20
    So 25cm3 of a 100cm3 solution of FeSO4 is titrated against 0.02moldm-3 of 8.60cm3 of MnO4-
    So I calculated mol of mno4- and got 1.72x10-4 and multiplied this by 5 to get mOles of FeSO4
    My teacher said to calculate mass of the 100cm3 solution and using the mass of the iron tablets (1.16g) and then do mass/mass of the iron tablets but I'm really confused as to how the mass of the 100cm3 solution divided by the mass of the iron tablets tells you the percentage? Can anyone explain?
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by AqsaMx)
    So this is the redox equation provided
    5fe2+ + MnO4- + 8H+ --> 5Fe3+ + Mn2+ + 4H20
    So 25cm3 of a 100cm3 solution of FeSO4 is pipettes again 0.02moldm-3 of 8.60cm3 of MnO4-
    So I calculated mol of mno4- and got 1.72x10-4 and multiplied this by 5 to get mOles of FeSO4
    My teacher said to calculate mass of the 100cm3 solution and using the mass of the iron tablets (1.16g) and then do mass/mass of the iron tablets but I'm really confused as to how the mass of the 100cm3 solution divided by the mass of the iron tablets tells you the percentage? Can anyone explain?
    The final answer is 16.6% btw
    • Thread Starter
    Offline

    3
    ReputationRep:
    Anyone?
    Offline

    0
    ReputationRep:
    100cm3 is the intial volume.

    moles of Fe in 25cm3 = 8.6x10-4 moles
    moles Fe in 100cm3 = (8.6x10-4) x 4 = 3.44x10-3
    mass of Fe = moles x mr = (3.44x10-3) x 55.8 = 0.192 grams
    % mass = mass Fe/mass tablets x 100 = 0.192/ 1.16 x 100 = 16.54%
    Offline

    0
    ReputationRep:
    lool i realised im 3 weeks late
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Has a teacher ever helped you cheat?
    Help with your A-levels

    All the essentials

    The adventure begins mug

    Student life: what to expect

    What it's really like going to uni

    Rosette

    Essay expert

    Learn to write like a pro with our ultimate essay guide.

    Uni match

    Uni match

    Our tool will help you find the perfect course for you

    Study planner

    Create a study plan

    Get your head around what you need to do and when with the study planner tool.

    Study planner

    Resources by subject

    Everything from mind maps to class notes.

    Hands typing

    Degrees without fees

    Discover more about degree-level apprenticeships.

    A student doing homework

    Study tips from A* students

    Students who got top grades in their A-levels share their secrets

    Study help links and info

    Can you help? Study help unanswered threadsRules and posting guidelines

    Sponsored content:

    HEAR

    HEAR

    Find out how a Higher Education Achievement Report can help you prove your achievements.

    Groups associated with this forum:

    View associated groups
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • 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.