I guess you could try the blue glass trick the book suggests as it is rather difficult/expensive to make/buy perchloric/chloroplatinic acid.Tests for Potassium Compounds-The potassium flame is violet, but is easily masked by the intense yellow of the sodium flame. It is well to view the flame through a thick blue glass which cuts off the yellow light.
The potassium ion unites with the chloroplatinate ion to form insoluble potassium chloroplatinate, K2PtCl6. The precipitate is composed of yellow octahedra. The solution of potassium salt must be rather concentrated and precipitation is aided by addition of a little alcohol. This reaction is the basis of a standard method of determining potassium quantitatively. Due to the great expense of the chloroplatinic acid the perchlorate method is coming into use. perchloric acid is added to a solution of a potassium salt. While potassium perchlorate, KClO4, is precipitated, particularly in the presence of alcohol.
https://www.physicsforums.com/images/smilies/laughing.gif [Broken]cantbemessedwit said:can the presence of potassium be determined with a chemical test? if so how? If potassium is heated in a bunsen burner flame , would the flame be yellow?
I very much doubt a chemical test for potassium in coffee would ever be positive, the concentrations would be extremely low with many impurities. Personally i would use a hyphenated analytical technique like HPLC-AAS and compare to a set of standards as you'd be able to detect ppm concentrations easily.
Perhaps you could say that potassium is a 'special' emitter or that our 'crude' detectors fail to accurately show its sublime but beautiful brilliance?Potassium is a WEAK emitter.
Didn't notice the dates.Viterbo's response is almost a year old... (11-10-2006) and SHAME on you for dissing potassium!
Perhaps you could say that potassium is a 'special' emitter or that our 'crude' detectors fail to accurately show its sublime but beautiful brilliance?