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Author: Subject: Ammonia houshold cleaner + NaOH: What does this do or make?
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[*] posted on 12-12-2015 at 18:06
Ammonia houshold cleaner + NaOH: What does this do or make?

Since both are bases and NaOH is the stronger of the two, what exactly happens (chemically) when the two are mixed? When I did this I noticed that the ammonia vapors were liberated after a couple of seconds sitting on the beads. It produced bubbles and heat then the mixture turned clear, like water and when it started to cool it started to cloud, then got thick, tacky and a semi-translucent white color. Adding more H2O to it didn't seem to do anything except dissolve the tacky paste.

Could someone explain a little what happened here and what was the end product? If I wanted to get a higher concentration of ammonia than the grocery store (what is it 3-8%??) version, could I add the ammonia liquid to the NaOH and condense the vapors in something like a dry ice/alcohol bath or have the vapors been changed into something else? Finally what % ammonia can be had by this process (if it is indeed pure ammonia being driven off)?
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[*] posted on 12-12-2015 at 18:22

Ammonia in water gives the following equilibrium:
NH3(gas) + H2O(aq) <--> NH4⁺(aq) + OH⁻(aq)
By adding another base to the aforementioned solution you will shift the equilibrium to the left and produce gaseous ammonia (until it stabilizes again).
Not sure about the tacky paste.
You could get near pure ammonia by working with the gases produced by this reaction... but I'm not so sure you could liquefy it only by cooling the gas without pressurizing it.

In general people use ammonia generators based on the reaction of saturated basic solutions with ammonium salts since those are readily available in good purity and produce ammonia gas upon reaction without the mess of the bunch of water present in the household ammonia cleaning products.

[Edited on 13-12-2015 by battoussai114]

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[*] posted on 13-12-2015 at 13:48

I'm guessing but I think the household ammonia tacky paste is some sort of stabilizer the manufacturer put in to prevent outgassing of NH4 on the shelf.

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[*] posted on 13-12-2015 at 14:32

It would help to know roughly how much sodium hydroxide and ammonia solution was used.
If the amount of sodium hydroxide used was equal to or greater than the amount of the ammonia solution, then my guess is the heat from the dissolving sodium hydroxide drove off most/all of the ammonia, leaving a hot, concentrated solution of sodium hydroxide, which solidified to the "tacky paste".

Also, per this, many brands of clear household ammonia are "<3%".

[Edited on 13-12-2015 by MolecularWorld]

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[*] posted on 14-12-2015 at 00:03

When you mix NaOH and ammonia no particular reaction occurs. NH3+H2O already is nearly 100% NH3 and H2O and hardly any NH4(+) and OH(-) are in such solutions.

NH3, however, does not dissolve as well in concentrated solutions of NaOH as in plain water. So, if you add NaOH to concentrated NH3 (e.g. 25% or so), then you get bubbles of NH3 escaping from the liquid. HaOH plus water also produces heat and this also contributes to driving off gaseous NH3.

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