March 28, 2024, 04:23:40 PM
Forum Rules: Read This Before Posting


Topic: Concentration of ions in half-cell for measuring standard electrode potential  (Read 3979 times)

0 Members and 1 Guest are viewing this topic.

Offline mystreet123

  • Regular Member
  • ***
  • Posts: 24
  • Mole Snacks: +0/-0
Should we use 1moldm-3 or 2moldm-3 of H+ ion in the VO2(+)|VO(2+) half-cell? and why?

Thanks in advance!

Offline Hunter2

  • Sr. Member
  • *****
  • Posts: 2153
  • Mole Snacks: +162/-47
  • Gender: Male
  • Vena Lausa moris pax drux bis totis
Please write the Nernst equation for this case.

Offline mystreet123

  • Regular Member
  • ***
  • Posts: 24
  • Mole Snacks: +0/-0
Please write the Nernst equation for this case.

We didn't learn this in high school...

Offline Hunter2

  • Sr. Member
  • *****
  • Posts: 2153
  • Mole Snacks: +162/-47
  • Gender: Male
  • Vena Lausa moris pax drux bis totis

Offline Hunter2

  • Sr. Member
  • *****
  • Posts: 2153
  • Mole Snacks: +162/-47
  • Gender: Male
  • Vena Lausa moris pax drux bis totis
The Nernst equation is:

E = E0 + 0,059 V/1 * (cVO2+ *c2H+)/cVO2+

If E = E0 = 1 V what has to be the concentration of each component.
« Last Edit: May 17, 2016, 09:59:32 AM by Hunter2 »

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27633
  • Mole Snacks: +1799/-410
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Nernst equation doesn't matter.

What is the definition of "standard electrode potential"? What is "standard" about?
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline mystreet123

  • Regular Member
  • ***
  • Posts: 24
  • Mole Snacks: +0/-0
Nernst equation doesn't matter.

What is the definition of "standard electrode potential"? What is "standard" about?

I know the standard condition means the components have to be in 1 moldm-3 but I thought as the vanadium ion used is already 1moldm-3, 2moldm-3 of H+ should be used to fit the equation above...

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27633
  • Mole Snacks: +1799/-410
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
I know the standard condition means the components have to be in 1 moldm-3

And that's all that matters - all substances present must have their concentrations (or more precisely: activities) equal to 1. Doesn't matter what the reaction is.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline mystreet123

  • Regular Member
  • ***
  • Posts: 24
  • Mole Snacks: +0/-0
I know the standard condition means the components have to be in 1 moldm-3

And that's all that matters - all substances present must have their concentrations (or more precisely: activities) equal to 1. Doesn't matter what the reaction is.

How about Al3+(aq)|Al(s) half-cell? Can I use 0.5moldm-3 Al2(S04)3 but it also means SO4 2- ions are in 1.5moldm-3 concentration?

Offline Hunter2

  • Sr. Member
  • *****
  • Posts: 2153
  • Mole Snacks: +162/-47
  • Gender: Male
  • Vena Lausa moris pax drux bis totis
I think so. The Sulfate doesn't take place in the reaction.

Sponsored Links