Salinity test residue

[DrewLG]

What is the white residue left in the test vial after the salinity test, and more importantly, what dissolves it? It doesn't seem to be soluble in water or alcohol, and I'm not sure that my current mechanical cleaning method is removing all of it.

 

[PoolStored]

Rubbing Alcohol has worked fine for me, I use the 90-92%, and a bleach/water solution work.

Is it scratched? Shouldn't need mechanical to get it off, that may have scratched it. I use coffee filters, they don't leave fuzz...

 

[AUSpool]

Use household ammonia to clean the test vial and then rinse a few times. Run some ammonia in the magnetic stirrer that way you clean the spinner too. I use a separate test vial and spinner for the salt test.

 

[AUSpool]

The test residue is mostly silver chloride, an insoluble white precipitate. The silver nitrate will react with all the chloride first then at the end point when all the chloride ions are ‘used up’ it will react with the chromate forming the brick red silver chromate. Ammonia is the ideal solvent hear.

 

[JoyfulNoise]

Ammonia is the ideal solvent hear.

Solutions of potassium cyanide work well too ... but you only get to make one mistake with that solution

 

[PoolStored]

Use household ammonia to clean the test vial

First time I've heard this. Will recommend then...

 

[JamesW]

Deleted.

 

[JamesW]

Sodium thiosulfate and hydrochloric acid will also dissolve the precipitate.

 

[DrewLG]

Solutions of potassium cyanide

Sodium thiosulfate

Sodium thiosulfate cures cyanide poisoning, so I guess I could use a mixture of both...

Use household ammonia to clean the test vial and then rinse a few times. Run some ammonia in the magnetic stirrer that way you clean the spinner too.

Or I could use ammonia -- which I'm sure @JamesW and @JoyfulNoise would have recommended, too, but you got there first. Thank you.

 

[AUSpool]

Ammonia is cheep from the grocery store and you don’t need much. As a bonus it is also good for cleaning circular saw blades, router and drill bits. I used 50% ammonia, 50% water and some dish detergent and they look like new.

 

[JamesW]

In this reaction, silver chloride (AgCl) reacts with ammonia (NH3) to form a complex ion called silver ammine ([Ag(NH3)2]+) and chloride ion (Cl-).

The balanced equation shows that 1 mole of AgCl reacts with 2 moles of NH3 to produce 1 mole of [Ag(NH3)2]+ and 1 mole of Cl-.

AgCl + 2NH₃ --> AG(NH₃)₂⁺ + Cl^-

 

[JamesW]

Silver chloride dissolves in methylamine.

https://www.sigmaaldrich.com/US/en/product/sial/426466



AgCl + 2CH₃NH₂ --> Ag(CH₃NH₂)₂⁺ + Cl^-

https://www.perplexity.ai/search/explain-why-silver-chloride-is-2fTM1A0uQM.pkcj2jg8cSw

Methylamine has a strong, pungent, acrid smell that’s similar to rotten fish.

It’s also a carefully controlled substance, as it’s on the DEA watchlist because it’s used in the manufacture of the drugs MDMA (also known as ecstasy) and methamphetamine.

https://airgasspecialtyproducts.com/what-is-methylamine-what-are-its-application-uses

 

[AUSpool]

Versatile stuff, used to make everything from animal supplements to rocket propellants.

And I like that term “displaces the equilibrium”, easily applied to pool chemistry.

I tried bleach and acid (HCl), not at the same time although that would get me new vial and I could probably reuse the spinner after prying it out of the ceiling.

They both worked to some degree but not as good as the ammonia. Don’t know where I heard about the ammonia but it sure works a treat. Saying silver chloride forms a white precipitate conjures the thought of white fluffy snow that slowly drifts to the bottom of the vial but that stuff sticks like supper glue.

The ammonia is a bit stinky. A little bit in a test vial wasn’t too bad but enough to cover a saw blade in the bottom of a plastic bucket was definitely an outside job. And I really should have worn gloves but it turns out that ammonia is really good at removing paint stains.