So! I'm not a chemist but the rudimentary research I did is below:
This is a link to the chemistry reaction and a balancer to find out what you need. The important part is:
One mole of aqueous Ammonium Sulfate [(NH4)2SO4] and two moles of aqueous Sodium Nitrite [NaNO2] react to form four moles of liquid Water [H2O], two moles of Dinitrogen [N2] gas and one mole of aqueous Sodium Sulfate [Na2SO4]
Idk if you're super familiar with chemistry but you have to make sure you have the moles right. Ammonium sulfate, when heated, releases ammonia, sulfur dioxide, sulfuric acid vapors. And you will produce that gas alongside the N2 because reactions are imperfect. So its important that as much of the ammonium sulfate reacts with the sodium nitrite as possible, but absolutely use a fume hood so you don't accidentally expose yourself to uhhh all of that lol.
The other gas released is N2 as I mentioned! The product (sodium sulfate) is soluble in water, so the water it produces will have the sulfate dissolved in it. Ammonium sulfate and sodium sulfate are often used as fertilizers apparently, so its not dangerous to dump but bad to ingest. That being said:
Chemistry Website for the Reaction
If you ctrl+f on here and search for 'sodium sulfate' (the byproduct) you'll see the disposal methods / info.
Search the page for Ammonium Sulfate. This is where it says "It decomposes on heating to release ammonia, sulfur dioxide, sulfuric acid vapors."
The hot plate the guy is using in the video has a magnetic stirring bar in it. Whether or not thats necessary for the reaction remains to be seen but I'm pretty sure it just speeds up the process and ensures it all reacts.
NileRed Chemistry Safety Vid
NileRed is one of my favorite chemistry youtubers. He goes over PPE just in case.
So yeah! You should look into how to get the molarity of the solutions you'll be using, or how to get what you need anyway. Even when you do, use a fume hood. Careful with the powder form of ammonium sulfate, too because some of these things seem to irritate airways n stuff. But if I were you, I wouldn't just throw in 0.5ml of each if you don't know the concentration. I'm not good at molarity or math! If you make the solutions yourself you'll be certain of the concentration but again, double check stuff. This is probably not the most dangerous reaction a person could do, I mean the video has him doing it in a classroom to show (probably) the actual reaction since its used quite a bit when balancing the equations. I saw it a bunch anyway. Nonetheless you can dump the whole thing once the reaction is over, and AFTER its cooled down to room temperature. Make sure the container you use is large enough that even if the solution comes to a rolling boil, it won't splash out. Beakers and whatnot are good for that.
I don't know how much you know about chemistry so I figured I'd dump all the stuff I found! Anyway that's all I got. This was super fun to look into!
Other Sources I used(tm)
Sodium nitrite react with ammonium sulfate to produce nitrogen, sodium sulfate and water. Sodium nitrite and ammonium sulfate - saturated solutions. The reaction takes place in a boiling solution. Source: https://chemiday.com/en/reaction/3-1-0-8634
Good Old Wikipedia
