Blue Lake Test: Tips to Get it Right in Chem Lab

[asad]

blue lake test...HELP

aluminium ions presence in a salt is confirmed by performing a test called blue lake test i have been trying to get it rught in my chem lab for weeks but in vain can anyone suggest the exact method i should use the way i perform the test is that i take solution of aluminium salt in a test tube add few drops of litmus solution then acidify with dil. HCl then add NH4OH(ammonium hydroxide) and allow to stand . the result i should get is blue ppt. floating in colourless solution but i haven't got this result at all can anyone help me perform the test better?

 

[chem_tr]

Maybe you need to review what's been happening in the experiment. You add litmus, whose color is blue in alkaline solutions. It is possible that the concentration of HCl is too low to provide required acidity, but ammonia solution is more concentrated than HCl to yield a basic solution eventually. I do not think that the precipitate is actually blue, it is colored by litmus; I recall that [Al(NH₃)₆]³⁺ is colorless, and I think you got this compound in your experiment.