Ammonia solution

• BPStrong Ammonia Solution
• JPAmmonia Water
• Ph. Eur.Ammonia Solution, Concentrated
• USP–NFStrong Ammonia Solution

Ammonia water; ammonium hydroxide; aqua ammonia; spirit of hartshorn; stronger ammonia water; E527

Ammonia (aqueous solution) · [7664-41-7]

UNII 5138Q19F1X · PubChem CID 222

NH3 · 17.03

pH adjuster, buffering agent

Typical concentrations: — · Dosage forms: Liquid

Used, usually after dilution, as an alkalising agent and for pH adjustment, as a buffer component with ammonium salts, and to form ammonium salts of acidic polymers such as shellac and some enteric coatings so they can be applied from aqueous solution. It has also been used in liniments and aromatic ammonia preparations.

A clear, colourless liquid with a very pungent, characteristic odour; it is strongly alkaline and caustic.

Strength

strong/concentrated solutions contain about 25–31% w/w NH3 (USP–NF Strong Ammonia Solution 27–31%; Ph. Eur. concentrated 25–30%); dilute solutions about 10%

Density

≈ 0.89–0.91 g/cm³ for the strong solution

pKa

9.25 (ammonium ion, 25 °C)

Alkalinity

strongly alkaline; a 1 M solution has a pH of about 11.6

Volatility

loses ammonia gas readily, especially when warm

Ammonia escapes from the solution, so strength falls in partly filled or poorly closed containers and pressure builds up in warm conditions. Store in a tightly closed container in a cool place, preferably below about 20 °C, and cool before opening.

Reacts vigorously with acids and acid anhydrides, and with halogens and hypochlorites. With silver, mercury and gold salts and with iodine it can form explosive compounds. It attacks copper, brass and zinc.

Ammonia is synthesised from nitrogen and hydrogen by the Haber–Bosch process and the gas is dissolved in purified water to the required strength.

Dilute solutions at the concentrations remaining in finished products are of little concern. The strong solution is corrosive to skin, eyes and mucous membranes; its vapour is a severe respiratory irritant and swallowing it causes serious burns.

Handle the strong solution in a fume cupboard with gloves, goggles or a face shield and protective clothing. Open containers slowly after cooling, as they may be under pressure.

Ammonium hydroxide is GRAS listed and accepted as a food additive in Europe (E527). Included in the FDA Inactive Ingredient Database (for pH adjustment in several dosage forms) and in medicines licensed in Europe.

Dilute ammonia solution (about 10% NH3); ammonium carbonate; ammonium chloride.

Because ammonia is volatile, much of it is lost on drying of coatings, which is useful for aqueous enteric coatings applied as ammonium salts. The strength of stock solutions changes with time and should be checked by titration before use in critical formulations.