# KNO3 solution cloudy



## AndreiD (16 Dec 2016)

Hello , recently i switched the KNO3 powder , i bought from other aquarium shop. And when i mixed it with water the solution became cloudy , but it was cold (same as the old KNO3 solution) , this because it contains nitogen . 

And my question is : is it normal for the solution to become cloudy ? , even second day after mixing the powder with water ?

Thanks


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## dw1305 (16 Dec 2016)

Hi all, 





AndreiD said:


> And when i mixed it with water the solution became cloudy , but it was cold (same as the old KNO3 solution) , this because it contains nitogen .


It definitely shouldn't be cloudy, unless it is really cold and you are right up by the solubility limit? It is a soluble compound, solubility is 316 g/L at 20°C, and 133 g/L at 0°C. 

You are right that the solution will get colder as the salt dissolves (the reaction is endothermic, because it takes more energy to break the K - NO3 bond than is released) and no new bonds are formed. 

cheers Darrel


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## AndreiD (16 Dec 2016)

dw1305 said:


> Hi all, It definitely shouldn't be cloudy, unless it is really cold and you are right up by the solubility limit? It is a soluble compound, solubility is 316 g/L at 20°C, and 133 g/L at 0°C.
> 
> You are right that the solution will get colder as the salt dissolves (the reaction is endothermic, because it takes more energy to break the K - NO3 bond than is released) and no new bonds are formed.
> 
> cheers Darrel



Thanks Darel , but how can i be sure its KNO3 and not CaNO3 or something else ?
This is my concern
I added 45 gr of powder to 500 ml still water , can be because of still water ? i'll try with boiled water and then chill the water and mix it with the powder


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## dw1305 (16 Dec 2016)

Hi all, 





AndreiD said:


> Thanks Darel , but how can i be sure its KNO3 and not CaNO3 or something else ?


Not easily, unfortunately without access to a flame photometer etc. 

If you've got a bunsen burner (or even a gas cooker) you can try burning a small amount of the salt in the flame (you can put it on a metal spoon). The flame should go lilac tinged (you may have to add a small volume of sugar). 



There aren't many insoluble potassium compounds, but  Lamotte do a test kit <"Potassium Test Kit Order Code: 3138-01">.

cheers Darrel


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## AndreiD (16 Dec 2016)

Ok, thanks , i will try that


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## AndreiD (16 Dec 2016)

Haven't done the "fire test " yet but this powder has pungent smell (but not like ammonia) .
Anyone else can confirm this ?


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## jolt100 (17 Dec 2016)

Calcium nitrate dissolves readily and gives a clear solution. The Industrial grade I use may have a surface coating to keep free flowing but is still only slightly hazy. Potassium nitrate doesn't have any odour.
It could be some contamination.  When you say it's got a pungent smell do you mean sharp, like vinegar, or sulphurous like rotten eggs?
If it's contaminated with another salt you could get a white precipitation, eg if you add KNO3 to MgS04 both are clear solutions but give a turbid mixture. 
I would return it to the shop rather than risk it.

Cheers 
John


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