Is Potassium Detectable with a Chemical Test?

[cantbemessedwit]

[SOLVED] Is there potassium in coffee

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?

 

[mrjeffy321]

I assume you mean Potassium ions, not Potassium metal (I would avoid heating that in a flame).
If you perform a flame test with the K+ ion, the flame, ideally, should be violet/lilac, not yellow (yellow indicates Sodium).
However, just because you get a yellow, Sodium, flame, does not necessarily indicate that there are no Potassium ions in solution. Potassium gives a very weak flame test and is easily overpowered by the colors given off by impurities, especially Sodium.

Is there Potassium in coffee? Is there anything to indicate that there is as listed on the nutrition facts?

 

[cantbemessedwit]

the presence of potassium ions

what would be a reason that potassium ions could not be detected when doing a chemical test with coffee? 4 day old coffee where potassium doesn't decompose

 

[Cesium]

It is difficult to detect the presence of potassium ions without sophisticated chemical instruments. As mrjeffy321 states, a chemical flame test will not work because sodium's yellow flame will overpower the lilac flame color of potassium.

Here is a section from an old chemistry book I have that may help you out:

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.

I guess you could try the blue glass trick the book suggests as it is rather difficult/expensive to make/buy perchloric/chloroplatinic acid.

 

[Viterbo]

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.

 

[amandeep]

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?

https://www.physicsforums.com/images/smilies/laughing.gif

 

[live18]

You know what, i think i have seen this in coffe in a mini store, it said it in the label, so i think there is such a thing.

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http://hghlook.com"

 

[chronon]

Coffee is relatively high in potassium. It's one of the things that you have to cut out if you have defective kidneys, as having double the normal amount of potassium in your bloodstream is likely to make your heart stop. You can find more information than you are ever likely to want about the composition of foods at http://www.nal.usda.gov/fnic/foodcomp/Data/SR18/reports/sr18page.htm

 

[ale]

potassium in coffe

I just want to understand the prove of potassium in coffe where
K2Na[Co(NO2)6] is the precipitate obtained

 

[ale]

I just want to understand the prove of potassium in coffe where
K2Na[Co(NO2)6] is the precipitate obtained

 

[Jeff Corkern]

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.

It's easier than that.

I am an environmental chemist. I spent years running an ICP-AES, an Inductively-Coupled Plasma---Atomic Emission Spectrometer. Basically, you fire up an argon plasma at 5000C or so, (not sure), squirt the solution into it and measure the light given off the metallic elements.

ICP's are pretty tough. You could run the coffee straight into it if you wanted, although you'd probably have to clean it afterward. More than likely you'd dilute the coffee by a factor of around 1000 and run that because the potassium signal would be so high.

Minimum Detection Limit for potassium by ICP is around 0.5 ppm. Which is about the highest MDL for routine elements by ICP. Potassium is a WEAK emitter.

Jeff Corkern
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[chemisttree]

Viterbo's response is almost a year old... (11-10-2006) and SHAME on you for dissing potassium!

Potassium is a WEAK emitter.

Perhaps you could say that potassium is a 'special' emitter or that our 'crude' detectors fail to accurately show its sublime but beautiful brilliance?

 

[Jeff Corkern]

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?

Didn't notice the dates.

Hey! Can I help it if potassium is a wuss element?

Jeff Corkern
--------------------------------------------------------------------------------------
Consider the following as a statement of logic and rank it as "True" or "False."

"If people possesses immortal souls, it should be possible to deduce this by logical analysis of their behavior."

www.theninepointfivetheses.blogspot.com

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