Sciencemadness Discussion Board

Ammonium Persulfate decomposition

RU_KLO - 29-10-2022 at 17:24

Hi,

regarding Wiki:

When heated to 120°C, ammonium persulfate decomposes releasing sulfur oxides, nitrogen oxides, oxygen and ammonia.

Could this be used to make ammonia solution? (or the other oxides will interfere)

if yes, should be heated as salt or (saturated) solution? (if heated as salt, could explode?) - from little experience, if salt lands on hot plate it crackles.

or

Is there a way to make ammonia Solution from ammonium persulfate? (I have a lot of and need some ammonia solution. Better if concentrated)

Thanks

Bedlasky - 29-10-2022 at 22:50

Quote: Originally posted by RU_KLO  
Could this be used to make ammonia solution? (or the other oxides will interfere)


No, it cannot be used this way. Sulfur and nitrogen oxides are all acidic, so you rather get mix of ammonium sulfate, sulfite and nitrate.

For making ammonia generator use some cheap ammonium salt like chloride or sulfate, and sodium hydroxide. You can surely find some procedure here on forum.

Alkoholvergiftung - 29-10-2022 at 22:58

Why not reakt an ammoniumsalt with an hydroxide? CaOH and dropping an concentrated ammoniumchlorid or sulfat solution on it?

Mateo_swe - 30-10-2022 at 00:53

Or maybe just buy some ammonium solution?
Its available in hardware/paint stores and not especially expensive.

RU_KLO - 30-10-2022 at 05:24

Thanks, I know that buying new reagents is always a solution. but currently the only ammonium salt Ive got is persulfate.... so the idea was to use available reagents.

Texium - 30-10-2022 at 08:10

That would be a waste of ammonium persulfate. Save it for better things.

woelen - 30-10-2022 at 11:18

Using ammonium persulfate for the sole purpose of making ammonia indeed is not very economical, but if you really want to do so, you can do it by mixing the salt with a slight excess of solid NaOH and then adding a few drops of water. A lot of gas will be produced, which is a mix of ammonia and oxygen. Bubble it through water, the ammonia is absorbed, the xoygen passes through.

You'll see a transient very peculiar yellow/orange color when the reaction proceeds. This definitely is caused by the peroxodisulfate reacting with hydroxide, but this does not affect the final outcome of the reaction. You'll get your ammonia.

Use care with the reaction, it will be quite exothermic. Start with small amounts to get a feeling of it.

RU_KLO - 31-10-2022 at 06:03

woelen thanks,

Tried and learned about ammonia suckback....