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KNO3 solution cloudy

AndreiD

Member
Joined
2 Dec 2015
Messages
156
Location
Oradea Romania
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
 
Hi all,
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
 
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
 
Last edited:
Hi all,
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
 
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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