testing KNO3

[aXiate]

is there a way to find out if i have KNO3, i found some stuff in a gardning section of my mates garage and i was wondering if it is KNO3,
is there a way of finding out it is?

[Dave Angel]

I know it may seem weird but apparantly, it tastes a lot like rhubarb (don't ask me why). Of course, if you don't know what that tastes like then I guess you are stuck! The whole toxicity thing is overrated, taste testing of chemicals is perfectly safe, in most cases.

Then again... you could always try the utfse test, but some people find that to be too much effort for such trivial things.

[EP]

Mix it with sugar in a roughly 50/50 mix, if it burns, it's probably KNO3.

[T_Pyro]

See if it lends a lilac colour to the blue flame of a burner. If so, it's a K salt. If you have any conc. sulfuric acid, add a little bit of the salt to about 1.5 ml of sulfuric acid. Evolution of some pungent brown fumes indicates the probable presence of a nitrate.

Alternatively, sprinkle some of the salt on a piece of paper, and heat it from underneath. If it's potassium nitrate, it'll soon catch fire, and travel over the paper as a molten ball, incinerating the paper as it travels.

[metafractal]

Dont trust the flame test for K salts. If it was found in the "gardening section" it will be impure, and even trace impurities of Na+ will turn the flame from lilac to bright yellow.

[Boomer]

The sugar test or the sulphuric acid test will show if it is a nitrate at all, or urea etc.

Melting point will show if it is NH4- or Na/K- NO3.

Solubility in hot/cold water will show whether Na- or K- NO3.

Simple! :)

[fire vs. water]

does anyone know how to test it for impurities?
my KNO3 leaves a lot of black shit after its burned with sugar, it creates stuff that looks like lava, and then it expands a lot and becomes black...
is this how it's supposed to act??

[atlas#11]

Add some more nitrate, sounds like you have too much sugar in their.

Add a chlorine donor so you can clearly see what color it burns at. if it's purple then it's KNO3 plain and simple, fertilizers supply nitrogen or phosphorus and it is not going to be KClO3 as that dosen't supply anything the plant needs. If it's pure enough to make a noticible purple flame then it is probably pure enough to be used in nitrations and what not. See if you can find any patent numbers or product numbers on the bag. You would be suprised of the chemical information avalible about most products these days. Search and you shall find.

[Mr Cool]

What you have described could be evidence of impurity, OR very poor mixing, very poor ratios, and/or components that are nowhere near fine enough.

[tmp]

The last bag of KNO3 fertilizer I bought had N-P-K rating: 13.5 - 0 - 45
This is pretty close to the numbers I got calculating based on atomic weights.
By this calculation pure KNO3 would be 13.8 - 0 - 46.5. Remember that K is
represented by available potash(K2O). Also KNO3 has a cool and bitter taste
to it. Just be sure to spit it out after tasting unless you're into temporary
impotence ! :)