Sciencemadness Discussion Board

Ammonium Hydroxide from Urea

Bason - 4-5-2018 at 22:16

Hello,

I want to make Schweizer's reagent to dissolve cotton for the production of Rayon (a fiber that imitates silk). The procedure for this experiment calls for a solution of ammonium hydroxide which is used to dissolve the precipitated copper(II) hydroxide. I plan to produce the ammonium hydroxide required in this experiment by the following set up:

-250mL Round bottom flask filled with small ammount of urea, NaOH, and water is heated on low-medium heat on a heating mantle.
- The flask is stoppered and connected to a rubber hose used to bubble the gas evolved into a tall graduated cylinder filled about 1/2 with distilled water.

My plan is that the reaction between urea and NaOH in solution under heat will produce ammonia gas which is then bubbled into the graduated cylinder and absorbed by the water - thus turning the distilled water into a somewhat concentrated solution of ammonium hydroxide which I can use in the Rayon experiment.

Note: I am aware that other alternatives can be used to produce ammonium hydroxide (such as using ammonium sulfate and NaOH, etc.); however, I only have urea and NaOH available and will be performing this experiment as a small-scale demonstration. Please give me some feedback on whether my proposed process will be effective in creating the ammonium hydroxide.

Thank you!

[Edited on 5-5-2018 by Bason]

[Edited on 5-5-2018 by Bason]

VSEPR_VOID - 4-5-2018 at 23:57

Your post is good but why not use household ammonia? I have made many copper complexes using regular ammonia without any problems arising. Remember to use a brand without many additives. If you need it to be more concentrated then you can dissolve ammonia gas into the household ammonia.

I do not have any experience generating ammonia by the reaction of sodium hydroxide and urea but I do recall that urea easily decomposes. According to the CDC, "The substance decomposes on heating above melting point, producing toxic gases, and reacts violently with strong oxidants, nitrites, inorganic chlorides, chlorites and perchlorates, causing fire and explosion."

Deathunter88 - 5-5-2018 at 00:08

Quote: Originally posted by VSEPR_VOID  
Your post is good but why not use household ammonia? I have made many copper complexes using regular ammonia without any problems arising. Remember to use a brand without many additives. If you need it to be more concentrated then you can dissolve ammonia gas into the household ammonia.

I do not have any experience generating ammonia by the reaction of sodium hydroxide and urea but I do recall that urea easily decomposes. According to the CDC, "The substance decomposes on heating above melting point, producing toxic gases, and reacts violently with strong oxidants, nitrites, inorganic chlorides, chlorites and perchlorates, causing fire and explosion."


Household ammonia isn't a thing for a lot of countries. In fact, I would argue that the majority of countries don't have such a thing.

VSEPR_VOID - 5-5-2018 at 00:23

My mistake then

unionised - 5-5-2018 at 02:53

I strongly recommend the use of some sort of anti "suck back" trap.