What is meant by aqueous ammonia solution?
Aqueous ammonia or aqueous solution of ammonia, also known as ammonia solution, ammonia water, ammonia liquor, ammoniacal liquor, aqua ammonia and finally ammonium hydroxide, is a solution of ammonia in water.
Ammonia is highly soluble in water. It has been experimentally found that at 273K temperature, 1000 volume of ammonia gas is dissolved in 1 volume of water. Because of ammonia molecules form very strong hydrogen bond with water molecule.
Aqueous ammonia or aqueous solution of ammonia is expressed as NH3 (aq.) or NH4OH. In practice, NH4OH compound has no existence.
That is, in aqueous solution, NH4OH is ionized and forms NH4+ and OH– ions. Hence the term ‘aqueous solution of ammonia’ is appropriate.
NH4OH (aq.) ⇌ NH4+ (aq.) + OH–(aq.)
What Is Liquor Ammonia?
At 273K temperature, thousand volume of ammonia is dissolved in one volume of water. The concentrated aqueous solution of ammonia of 0.88 specific gravities is called liquor ammonia.
It contains 35% ammonia in stoichiometric ratio. Liquor ammonia is a clear colorless liquid with strongly pungent odor. Chemically name of liquor ammonia is ammonium hydroxide.
What is aqueous ammonia formula?
Ammonia is more soluble in water. When ammonia is dissolved in water, ammonia takes H + ions from water molecules and turns into ammonium (NH4 +) ions.
This results in excess of NH4 + and OH– ions in the solution. This is why the aqueous solution of ammonia is called ammonium hydroxide.
Hence the formula of aqueous ammonia is NH4OH. Although in aqueous solution, there is no existence of ammonium hydroxide [NH4OH] molecule. Generally aqueous ammonia formula is expressed as NH3 (aq.).
What is pH of aqueous ammonia solution?
Ammonia is highly soluble in water. When ammonia dissolves in water, ammonia converts to ammonium (NH4 +) ions by taking H+ ions from water molecules and.
As a result, results in an excess of OH– ions in the aqueous solution of ammonia. Consequently, the aqueous solution of ammonia becomes mild alkaline.
The pH of 1M aqueous ammonia solution or ammonium hydroxide is 11.63. This solution turns red litmus into blue.
NH3 (g) + H2O (l) ⟶ NH4OH (aq)
NH4OH (aq.) ⇌ NH4+ (aq.) + OH–(aq.)
Aqueous ammonia solution that is, ammonium hydroxide neutralized acid resulting in the formation of concern salt and water.
2 NH4OH + H2SO4 ⟶ (NH4)2SO4 + 2H2O
Applications of aqueous ammonia solution
Laboratory uses
Aqueous ammonia solution cum ammonium hydroxide is an important laboratory reagent. Aqueous ammonia solution is used in qualitative analysis of inorganic compounds through complex formation. Like other amines, it gives a deep blue coloration with copper (II) solutions.
Aqueous ammonia solution can dissolve silver oxide residues, such as that formed from Tollens’ reagent. It is also used to clean silver, gold, and platinum in jewelry.
Household cleaner
Diluted aqueous ammonia solution (1% — 3%) is used as a household cleaner for many surfaces. This is because ammonia, as a cleanser, makes an object streak-free shine.
One of its most common uses is to clean glass, window, porcelain, and stainless steel. It is also used for cleaning ovens and soaking to loosen bakes-on grime.
Alkyl amine precursor
Aqueous ammonia is used in industry as a pioneer of some alkyl amines. For example, hexamethylenetetramine is formed from aqueous ammonia and formaldehyde.
Again, ethylene diamine is made from aqueous ammonia and 1, 2-dichloroethane.
Treatment of straw for cattle
Aqueous ammonia solution is used to treat straw, producing “ammoniated straw” making it more edible for cattle.
Absorption refrigeration
In the past, vapor absorption cycles using water-ammonia systems were popular and widely used. Examples of this application of ammonia solution are the Electrolux refrigerator and the Einstein refrigerator.
Furniture darkening
In furniture-making, Ammonia fuming was traditionally used to darken or stain wood containing tannic acid.
After being sealed inside a container with the wood, fumes from the ammonia solution react with the tannic acid and iron salts naturally found in wood, creating a rich, dark stained look to the wood.
