Ammonium chloride

Ammonium chloride
IUPAC name Ammonium chloride
Other names Sal ammoniac
Identifiers
CAS number	12125-02-9 Y
ChemSpider	23807
EC number	235-186-4
RTECS number	BP4550000
SMILES [Cl-].[NH4+]
InChI InChI=1/ClH.H3N/h1H;1H3 Key: NLXLAEXVIDQMFP-UHFFFAOYAI
Properties
Molecular formula	NH4Cl
Molar mass	53.491 g/mol
Appearance	White solid hygroscopic
Odor	odorless
Density	1.5274 g/cm3
Melting point	338 °C (decomposes)
Solubility in water	29.7 g/100 mL (0 °C) 37.2 g/100 mL (20 °C) 77.3 g/100 mL (100 °C)
Solubility in alcohol	0.6 g/100 mL (19 °C)
Acidity (pKa)	9.245
Refractive index (nD)	1.642
Thermochemistry
Std enthalpy of formation ΔfHo298	−314.55 kJ/mol[1]
Standard molar entropy So298	94.85 J K−1 mol−1 [1]
Hazards
MSDS	ICSC 1051
EU Index	017-014-00-8
EU classification	Harmful (Xn) Irritant (Xi)
R-phrases	R22, R36
S-phrases	(S2), S22
NFPA 704	0 1 0
Flash point	Non-flammable
LD50	1650 mg/kg, oral (rat)
Related compounds
Other anions	Ammonium fluoride Ammonium bromide Ammonium iodide
Other cations	Sodium chloride Potassium chloride Hydroxylamonium chloride
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Ammonium chloride NH₄Cl (also Sal ammoniac, salmiac, nushadir salt, sal armagnac, sal armoniac, salt armoniack) is, in its pure form, a clear white water-soluble crystalline salt of ammonia. The aqueous ammonium chloride solution is mildly acidic. Sal ammoniac is a name of natural, mineralogical form of ammonium chloride. The mineral is especially common on burning coal dumps (formed by condensation of coal-derived gases), but also on some volcanoes.

Sources

The substance occurs naturally in volcanic regions, forming on volcanic rocks near fume-releasing vents. The crystals deposit directly from the gaseous state, and tend to be short-lived, as they dissolve easily in water. It is a by-product of the Solvay process used to produce sodium carbonate.^[2]

Ammonium chloride is prepared commercially by reacting ammonia (NH₃) with hydrogen chloride (HCl). As these chemicals are corrosive, this process has to be performed in vessels lined with nonreactive materials (e.g. glass, enamel, lead, or PVC).^[2]

NH₃ + HCl → NH₄Cl

This reaction can occur if poorly sealed bottles of household ammonia (ammonium hydroxide) and hydrochloric acid are stored in close proximity, leading to crystals forming around the openings of the bottles (mostly appear on those leaking more slowly).

Reactions

Ammonium chloride appears to sublime but this process actually involves decomposition into ammonia and hydrogen chloride gas.^[2]

NH₄Cl → NH₃ + HCl

Ammonium chloride may be reacted with a hydroxide base, e.g. sodium hydroxide, to release ammonia gas:

NH₄Cl + NaOH → NH₃ + NaCl + H₂O

If test tubes of ammonia solution and hydrochloric acid are brought close together, a smoke composed of microcrystals of ammonium chloride will slowly rise out of the tube.

Applications

Ammonium chloride crystal(s).

Chemistry and Physics

Ammonium chloride dissolved in water becomes an acid. Ammonium chloride is used to produce low temperatures in cooling baths. For example, the zero point of Fahrenheit temperature scale is determined by placing the thermometer in a mixture of ice, water, and ammonium chloride. Ammonium chloride solutions with ammonia are used as buffer solutions.

Biology and Agriculture

In biological applications ammonium chloride acts as a nitrogen source and is used in fertilizers, as a feed supplement for cattle and as an ingredient in nutritive media for yeast microbiological organisms.

Pyrotechnics

Ammonium chloride is an ingredient in fireworks and safety and contact explosives.

Textile and Leather

Ammonium chloride is used in the textile and leather industry in dyeing, tanning textile printing and to luster cotton.

Metalwork

Ammonium chloride is used as a flux in preparing metals to be tin coated, galvanized or soldered. It works as a flux by cleaning the surface of workpieces by reacting with the metal oxides at the surface to form a volatile metal chloride. It is sold in blocks at hardware stores for use in cleaning the tip of a soldering iron and can also be included in solder as flux.

Medicine

Ammonium chloride is used as an expectorant in cough medicine. Its expectorant action is caused by irritative action on the bronchial mucosa. This causes the production of excess respiratory tract fluid which presumably is easier to cough up.

Ammonium salts are an irritant to the gastric mucosa and may induce nausea and vomiting.

Ammonium chloride is used as a systemic acidifying agent in treatment of severe metabolic alkalosis, in oral acid loading test to diagnose distal renal tubular acidosis, to maintain the urine at an acid pH in the treatment of some urinary-tract disorders

Ammonium Chloride is also used as a diuretic in forced acid diuresis.

Food

In several countries ammonium chloride is known as sal ammoniac and used as food additive. The E number for ammonium chloride used as a food additive is E510.

Sal ammoniac is used to spice up dark sweets called salty liquorice and in the flavouring Salmiakki Koskenkorva for vodkas.

Sal ammoniac is also used in baking to give cookies a very crisp texture.

Other Applications

Ammonium chloride is used in a ~5% aqueous solution to work on oil wells with clay swelling problems. It is also used as electrolyte in Zinc–carbon batteries. Other uses include in hair shampoo, in the glue that bonds plywood, in cleaning products.

References