Turn on thread page Beta
    • Thread Starter

    why is 1 mol of cu2+ equivalent to 1 mol of s2o3 2-
    the question is: a 0.5g sample of brass is reacted with concentrated nitric acid to form a solution containing cu2+ and zn2+ ions. the solution is then neutralised. excess KI (aq) is added. the resulting iodine solution is titrated with 0.2 mol dm3 sodium thiosulfate and 25.2cm3 are required to reach the end point calculate the percentage by mass of copper and zinc in the brass.

    i got the half equations for cu2+ and thisoulfate to be:
    cu2+ 2e- ----> cu
    2S2O3 2- ----> S4O6 2- +2e-

    as you can see from my half equations there are 2 moles of thiosulfate and 1 mole of copper

    someone explain to me please
    •  Official Rep

     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.

University open days

  1. University of Bradford
    University-wide Postgraduate
    Wed, 25 Jul '18
  2. University of Buckingham
    Psychology Taster Tutorial Undergraduate
    Wed, 25 Jul '18
  3. Bournemouth University
    Clearing Campus Visit Undergraduate
    Wed, 1 Aug '18
How are you feeling in the run-up to Results Day 2018?
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


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

Groups associated with this forum:

View associated groups

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