Distinguishing a solution of ammonia from water?

Question

I said to add Copper (II) oxide to both and whichever one gives off the aromatic gas, is the solution of ammonia.

NH4OH(aq) + CuO(aq) -> Cu(OH)2(s) + NH3(g)
Blue precipiate formed. Aromatic Gas evolves.

H20(l) + CuO(aq) -> Cu(OH)2(s)
Blue precipitate forms.

Is this right? Are there any better chemical tests to distinguish between the two?

Answer 1

Not really

A small amount of a soluble copper (II) compound, typically CuSO4 added to a small; but clearly excessive amount of ammonia solution will produce the unique deep blue copper tetrammine solution Deep ultramarine blue SOLUTION. If you get precipitate, then you have too much CuSO4 for any NH3 concentration, and have proved nothing. Flame test and ammonia solution are typical simple unique tests for copper

Cu2+ + 4NH3 -> Cu(NH3)4 2+ (aq).

HOWEVER, a simple careful wafting of the vapour from the ammonia solution ought be enough. If you can't smell it before dissolving the copper oxide in ammonia solution, then there is no chance of smeing it after the reeaction, which won't occur as CuO) is a very insoluble black powder.

So you have a means of determining ammonia moderately uniquely.

Water - can't think of a unique simple test.

Both your equations are wrong.

Answer 2

Your equations are not correct.
The way to distinguish between them with the same chemical is to add copper sulphate solution.
The water will just dilute it, and it will turn lighter blue. The ammonia, however, will first of all produce a blue precipitate of copper(II) hydroxide, which will then dissolve as you add more ammonia to form a dark blue complex - very distinctive.

Answer 3

In chemistry, the word 'aromatic' is reserved for certain conjugated pi-systems, and should not be used to describe something smelly, as this leads to confusion. You don't really need a chemical test to identify ammonia solution. It evolves ammonia spontaneously, so waving your nose anywhere near it will be a dead giveaway.

Answer 4

Lancenigo di Villorba (TV), Italy

I don't believe....
I executed someone of your chemical experiments in the past days...

REACTION.1)
You purposed the following chemical equation

NH4OH(aq) + CuO(aq) ---> Cu(OH)2(s) + NH3(g)

I AGREE NOT IT, so follows my reasons :
-) your equation obeys NOT to Fundamental Balancing's Criteria (see Lavoisier) ;
-) Copper(II) Oxide appears as a solid Blackish coloured powder IT RESULTS NOT ABLE TO DISSOLVE in aqueous media;
-) Ammonia is a smelling and harmful gas and IT RESULTS VERY ABLE TO DISSOLVE in aqueous media ;
-) several Copper(II) Compounds (e.g. you have to exclude some other ones, e.g. Cyano-Cuprates) RESULT ABLE TO DISSOLVE in Ammonia's Aqueous Solution in a GREATER MEASURE THAN Deionized Water do.

REACTION.2)
You purposed the following chemical equation

H2O(aq) + CuO(aq) ---> Cu(OH)2(s)

I AGREE NOT IT, so follows my reasons :
-) Copper(II) Oxide appears as a solid Blackish coloured powder IT RESULTS NOT ABLE TO DISSOLVE in aqueous media;
-) Copper(II) Oxide cannot back as Copper(II) Hydroxide meanwhile IT STANDS LONG-TERM in Deionized water.



Now, I show you my reasonings.
TOO DILUTED AMMONIA's Aqueous Solutions aren't able to dissolve the Copper(II) Oxide's powder.
On the other hand, if you use more concentrated stuffs you will see a BLUISH COLORATION appears in the liquid mixture while BRIGHT BLUE FLAKEs begins to form.

CuO(s) + 4 NH4OH(aq) --->
---> Cu(NH3)4(OH)2(s) + 3 H2O(aq)

You may explain it when you refer to Waage's MASS ACTION LAW (e.g. this law interests ONLY LIQUID MIXTUREs, it stated that THE GREATER THE REACTANT's CONCENTRATIONs, THE GREATER THE PRODUCT's FORMATION).
TOO CONCENTRATED AMMONIA'a Aqueous Solutions darkens the BLUE COLORATION while the FLAKEs are disappearing : the flakes undergo dissolution.

Cu(NH3)4(OH)2(s) ---> Cu(NH3)4++(aq) + 2 OH-(aq)

On the other hand, if you use more concentrated stuffs you will see the Copper(II) Oxide's Dissolution while a BLUISH COLORATION appears in the liquid mixture.


YOU DISTIGUISH AMMONIA's AQUEOUS SOLUTIONs FROM DEIONIZED WATER by the following main facts :
-) their smelling ;
-) Ammonia's evolvement at warm conditions ;
-) Blue-greenish coloration of Litmus Paper ;
-) Nessler Essay.
COPPER(II) OXIDE SPEAKING, IT MAY DISSOLVE IN AMMONIA's AQUEOUS SOLUTIONs WHILE THE LIQUID BECOME BLUISH COLOURED.

I hope this helps you.

Answer 5

Surely the easiest test is to measure the alkalinity. Ammonia will be much for alkaline than water.