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Topic: Determine an Unknown Salt in a lab  (Read 18582 times)

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arnyk

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Re:Determine an Unknown Salt in a lab
« Reply #15 on: June 17, 2005, 11:01:29 PM »
You could test for it in solution by dipping a wooden stick or wire into the solution and then placing the tip into a burner flame.  Of course this only works when there is a single salt in solution, multiple cations would contaminate the colours.
« Last Edit: June 17, 2005, 11:05:13 PM by arnyk »

Offline xiankai

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Re:Determine an Unknown Salt in a lab
« Reply #16 on: June 17, 2005, 11:33:21 PM »
but since sodium is in aqeuous mode, and the solid form burns with the characteristic yellow flame, are they the same? because seeing that u would evaporate the solution and possibly the sodium cations could be contained in the water vapour.
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arnyk

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Re:Determine an Unknown Salt in a lab
« Reply #17 on: June 18, 2005, 02:55:41 PM »
I believe the characteristic yellow flame occurs before any Na+ ions "evaporate" with the water.  I've never run into that problem before...can metallic ions evaporate?

Offline Borek

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Re:Determine an Unknown Salt in a lab
« Reply #18 on: June 19, 2005, 04:49:05 AM »
Flame test works for Na+. However, it is very sensitive (traces of Na+ give color) so it can easily give false positives. You should check that you don't get positive signal before adding tested salt to the solution.
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