[Rutherford]

I need some tips for analysing cations on fire using Bunsen burner (flame color charge), because I am going to do it for the first time.
1)Is it better to analyse solids, i.e. to place a solid salt on a wire and then to put it on fire or to dissolve the salt and then put the test tube which contains the salt solution on flame to see the flame color change?
2)What is the usage of HCl in these tests?
3)Does the color change depend on the anion in some cases?

[Arkcon]

More concentrated solutions are the best, but you want ions, so solids are at least slightly problematical.  A solid can still vaporize and ionize, but a solution is better than a precipitate.  An acid is a good way to be sure of ionization.  Nitrates are often favored, but HCl dissolves most metals that give definitive colors to flames.  Simple anions don't generally have a big effect, I'm talking chloride, nitrate, sulfate here: the flame color of metal salt where the anion contains a metal with a strong color itself is going to be a problem.  I had heard, for pyrotechnic pot fire, that copper salts in the presence of ammonium salt and chloride ion gives a strong blue color instead of green, so you should try to select very simple salts.

[Rutherford]

Thanks for the reply. I will get salts that are soluble in water. I am still unsure of what you said, is it better solid or in solution?

solids are at least slightly problematical.  A solid can still vaporize and ionize, but a solution is better than a precipitate.

Is it better to put a sample of the salt in a test tube, then add few drops of HCl, and put the tube on flame?

[Arkcon]

No.  That won't work at all, given the way you've described it.  Start here: http://en.wikipedia.org/wiki/Flame_test for all the possibilities, but a simpler write up is here: http://kdchemistry.blogspot.com/2009/10/flame-test-procedure.html

[Rutherford]

Okay, I am going to write how I understood it:
I put the salt in a test tube, then I add water, so it gets dissolved. After that, I put the wire into the solution, and then the wet wire is put on flame. After observing the color, I clean the wire by putting it in a HCl solution and testing again on the flame if it's clean.
Is this correct?

[Arkcon]

That's the method in the second reference.  Feel free to cut off and discard a section of the wire if the element colors the flame strongly -- copper comes to mind.  Also sodium taints everything when a flame test is done, do it last, or cut off the loop and throw it away before the next.  Potassium, in particular, is described as very faint.  In fact, I've never noticed anything with potassium.

[Rutherford]

I will just get an unknown salt, and I have to determine the cation by this test, so I will do it only once.
Thanks very much for the help, this is very important to me.