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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: student16 on December 21, 2005, 02:57:29 AM

Title: other barium and strontium tests
Post by: student16 on December 21, 2005, 02:57:29 AM

For school, we are testing an Unknown, and for Barium and Strontium
I've already tried flame tests, but could never get the supposed colors for the unknown or solutions of the ions.  Are there any other test to see if there are Barium or Strontium ionss?

Title: Re:other barium and strontium tests
Post by: Albert on December 21, 2005, 07:03:11 AM

Flame tests are still the best for discriminating between Barium and Strontium.

However, you can try this (I never did it: just read on a book): add dilute H2SO4 or copper sulfate.
Try to dissolve the precipitate with hydrochloric acid: SrSO4 is soluble, while BaSO4 isn't.

Title: Re:other barium and strontium tests
Post by: Alberto_Kravina on December 21, 2005, 03:39:20 PM

Try flame tests (as Albert said) Barium has a green color and strontium a brick-red flame.
The best way to distinguish the two cations, however, is trying to precipitate the Ba²⁺ with potassium chromate in acetic acid acid-sodium acetate buffer. Yellow precipitate shows Ba2+.
If Barium is present filter the chromate, neutralize with Na₂CO₃ and test for strontium with sulfate. White precipitate of SrSO₄ shows Sr

PS: Use a spectrometer to distinguish the colors.

Title: Re:other barium and strontium tests
Post by: student16 on December 21, 2005, 04:59:24 PM

alright thanks I try those