URGENT: chemistry titration aqa Watch

Badges: 5
Report Thread starter 1 month ago
A student weighed out a 2.29 g sample of impure K3[Fe(C2O4)3].3H2O and dissolved it
in water.
This solution was added to a 250 cm3 volumetric flask and made up to 250 cm3 with
distilled water.
A 25.0 cm3 portion was pipetted into a conical flask and an excess of acid was added.
The mixture was heated to 60 ºC and titrated with 0.0200 mol dm–3 KMnO4 solution.
26.40 cm3 of KMnO4 solution were needed for a complete reaction.
In this titration only the C2O4 2– ions react with the KMnO4 solution.

Question: Write an equation for the reaction between C2O4 2– ions and MnO4– ions in acidic
Calculate the percentage purity of the original sample of K3[Fe(C2O4)3].3H2O
Give your answer to 3 significant figures. (7marks)

I get all the steps apart from when determining the moles of K3[Fe(C2O4)3].3H2O
In the mark scheme moles of C2O4 in the original solution is being divided by 3 to find out its moles. Why?
TSR Jessica
  •  Official Rep
Badges: 16
Report 4 weeks ago
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.

Quick Reply

Attached files
Write a reply...
new posts
My Feed

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.


University open days

  • Solent University
    Postgraduate and Professional Open Evenings Postgraduate
    Mon, 25 Mar '19
  • Cardiff University
    Undergraduate Open Day Undergraduate
    Wed, 27 Mar '19
  • University of Portsmouth
    Postgraduate and Part-Time Open Evenings Postgraduate
    Wed, 27 Mar '19

Where do you need more help?

Which Uni should I go to? (147)
How successful will I become if I take my planned subjects? (78)
How happy will I be if I take this career? (135)
How do I achieve my dream Uni placement? (113)
What should I study to achieve my dream career? (77)
How can I be the best version of myself? (244)

Watched Threads

View All