March 04, 2021, 02:17:40 AM
Forum Rules: Read This Before Posting


Topic: Iodometric titration of copper  (Read 453 times)

0 Members and 1 Guest are viewing this topic.

Offline dlow

  • Regular Member
  • ***
  • Posts: 11
  • Mole Snacks: +0/-0
Iodometric titration of copper
« on: February 04, 2021, 11:11:49 AM »
Hi all.

After a bit of help trying to understand what I am doing in work.

I have just switched labs and I am now analysing copper via an iodometric titration with thiosulfate.

I get the basic chemistry of what is going on but it’s the method of EP determination that I am puzzled on.

All the information I have found on the internet involves a starch indicator and a colour change. In work it is automated using metrohm equipment but the end point is determined potentiometrically. I know that metrohm offer an electrode that can detect a colour change but it is not used. Instead a thermo platinum combination ORP electrode is used.

Can anybody tell me why this approach is used and recommend any literature I can read up about it please?

Thanks in advance.


Dave

Online chenbeier

  • Sr. Member
  • *****
  • Posts: 1278
  • Mole Snacks: +97/-21
  • Gender: Male
Re: Iodometric titration of copper
« Reply #1 on: February 04, 2021, 01:50:08 PM »
For automatic processes it is more easier to detect a voltage.  Every redox reaction create a electrical potential, calculated according Nernst.
For this reason it is also used for iodometric titration.
The same is measuring pH instead to use an indicator.

Offline dlow

  • Regular Member
  • ***
  • Posts: 11
  • Mole Snacks: +0/-0
Re: Iodometric titration of copper
« Reply #2 on: February 04, 2021, 03:54:46 PM »
Hi chenbeier.

Thanks for the response. I thought it might have been something basic like that but I just wanted to double check just to make sure. I had doubt because I also titrate Pb with EDTA using Metrohm's Optrode which uses colour change and this is automated. Go figure!!

As a follow on question then to my original one (to which I think I know the answer but I am just making sure)..

Even though the end point is determined potentiometrically and not by a colour change. Should I still be cautious about the same interfering elements I am reading about in journals when the end point is the traditional colour change?

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 26310
  • Mole Snacks: +1711/-402
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Iodometric titration of copper
« Reply #3 on: February 05, 2021, 02:59:22 AM »
Every method of EP detection has its own quirks.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Offline dlow

  • Regular Member
  • ***
  • Posts: 11
  • Mole Snacks: +0/-0
Re: Iodometric titration of copper
« Reply #4 on: February 05, 2021, 04:47:14 AM »
Hi Borek.

Thanks for the response.

Do you know of any literature out there that involves a potentiometric EP? I have had a good look on the internet but I haven’t found any regarding this specific type of titraton.

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 26310
  • Mole Snacks: +1711/-402
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Iodometric titration of copper
« Reply #5 on: February 05, 2021, 10:32:04 AM »
I doubt you will find anything on just this particular titration, it is in no way different from detecting the EP of any other potentiometric titration using ORP electrode.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Sponsored Links