What is the blue solution?

  • 5 Replies
  • 4956 Views

0 Members and 1 Guest are viewing this topic.

*

Offline Chemistry4me

  • Neilep Level Member
  • ******
  • 7709
    • View Profile
What is the blue solution?
« on: 21/02/2009 06:01:09 »
When ammonium vanadate (NH4VO3) is dissolved in dilute sulfuric acid and the solution is treated with an excess of sulphur dioxide, a blue solution is formed...
What is the blue solution? I have searched high and low and still can't find a definitive answer... [>:(][>:(]

*

Offline lightarrow

  • Neilep Level Member
  • ******
  • 4586
    • View Profile
What is the blue solution?
« Reply #1 on: 21/02/2009 08:22:17 »
When ammonium vanadate (NH4VO3) is dissolved in dilute sulfuric acid and the solution is treated with an excess of sulphur dioxide, a blue solution is formed...
What is the blue solution? I have searched high and low and still can't find a definitive answer... [>:(][>:(]
SO2 in acidic solution reduces VO3- (n.o. of vanadium = +5) to VO2+ (n.o. of vanadium = +4) which is blue.

*

Offline Chemistry4me

  • Neilep Level Member
  • ******
  • 7709
    • View Profile
What is the blue solution?
« Reply #2 on: 21/02/2009 11:33:00 »
Thanks lightarrow [:)]
I was wondering if it was VO2+
It appears that it is.

*

Offline Chemistry4me

  • Neilep Level Member
  • ******
  • 7709
    • View Profile
What is the blue solution?
« Reply #3 on: 22/02/2009 01:53:10 »
You know what the SO2 is oxidised to? SO32-? SO42-?

*

Offline lightarrow

  • Neilep Level Member
  • ******
  • 4586
    • View Profile
What is the blue solution?
« Reply #4 on: 22/02/2009 11:55:19 »
You know what the SO2 is oxidised to? SO32-? SO42-?
The last you have said. It's the only possibility, think about it. Which is the n.o. of S in SO2 and in SO32-? It's the same.  [:)]
So S is oxidized to +6, which means SO42- in water solution (or HSO4- in strong acidic solution).

By the way, the reaction from vanadate and SO2 is exploited industrially to make H2SO4; vanadium +4 is then re-oxidized by air to vanadium +5 and so it acts as catalyzer.
« Last Edit: 22/02/2009 12:12:19 by lightarrow »

*

Offline Chemistry4me

  • Neilep Level Member
  • ******
  • 7709
    • View Profile
What is the blue solution?
« Reply #5 on: 23/02/2009 02:51:22 »
Thank you [:)] again.
Haha, obviously I was NOT thinking!