Ammonium chloride

Ammonium chloride

Names
IUPAC name Ammonium chloride
Other names Sal ammoniac, Salmiac, Nushadir salt, Sal armagnac, Salt armoniack
Identifiers
CAS Number	12125-02-9 Y
ChEBI	CHEBI:31206 Y
ChemSpider	23807 Y
EC Number	235-186-4
Jmol 3D model	Interactive image
KEGG	D01139 Y
RTECS number	BP4550000
UNII	01Q9PC255D Y
InChI InChI=1S/ClH.H3N/h1H;1H3 Y Key: NLXLAEXVIDQMFP-UHFFFAOYSA-N Y InChI=1/ClH.H3N/h1H;1H3 Key: NLXLAEXVIDQMFP-UHFFFAOYAI
SMILES [Cl-].[NH4+]
Properties
Chemical formula	ClH4N
Molar mass	53.49 g·mol−1
Appearance	White solid, hygroscopic
Odor	Odorless
Density	1.5274 g/cm3
Melting point	338 °C (640 °F; 611 K) decomposes, sublimes
Boiling point	520 °C (968 °F; 793 K)
Sublimation conditions	Sublimes at 337.6 °C ΔsublHo = 176.1 kJ/mol
Solubility in water	244 g/L (−15 °C) 294 g/L (0 °C) 383.0 g/L (25 °C) 454.4 g/L (40 °C) 740.8 g/L (100 °C)
Solubility product (Ksp)	30.9 (395 g/L)
Solubility	Soluble in liquid ammonia, hydrazine, alcohol, methanol, glycerol Slightly soluble in acetone Insoluble in diethyl ether, ethyl acetate
Solubility in methanol	3.2 g/100 g (17 °C) 3.35 g/100 g (19 °C) 3.54 g/100 g (25 °C)
Solubility in ethanol	6 g/L (19 °C)
Solubility in glycerol	97 g/kg
Solubility in sulfur dioxide	0.09 g/kg (0 °C) 0.031 g/kg (25 °C)
Solubility in acetic acid	0.67 g/kg (16.6 °C)
Vapor pressure	133.3 Pa (160.4 °C) 6.5 kPa (250 °C) 33.5 kPa (300 °C)
Acidity (pKa)	9.24
Refractive index (nD)	1.642 (20 °C)
Thermochemistry
Specific heat capacity (C)	84.1 J/mol·K
Std molar entropy (So298)	94.56 J/mol·K
Std enthalpy of formation (ΔfHo298)	−314.43 kJ/mol
Gibbs free energy (ΔfG˚)	−202.97 kJ/mol
Pharmacology
ATC code	B05XA04 G04BA01
Vapor pressure	{{{value}}}
Related compounds
Other anions	Ammonium fluoride Ammonium bromide Ammonium iodide
Other cations	Sodium chloride Potassium chloride Hydroxylammonium chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Ammonium chloride, an inorganic compound with the formula NH₄Cl, is a white crystalline salt, highly soluble in water. Solutions of ammonium chloride are mildly acidic. Sal ammoniac is a name of the natural, mineralogical form of ammonium chloride. The mineral is commonly formed on burning coal dumps, due to condensation of coal-derived gases. It is also found around some types of volcanic vents. It is used as a flavouring agent in some types of liquorice. It is the product from the reaction of hydrochloric acid and ammonia.

Sources

It is a product of the Solvay process used to produce sodium carbonate.

CO₂ + 2 NH₃ + 2 NaCl + H₂O → 2 NH₄Cl + Na₂CO₃

In addition to being the principal method for the manufacture of ammonium chloride, this method is used to minimize ammonia release in some industrial operations. Ammonium chloride is prepared commercially by combining ammonia (NH₃) with either hydrogen chloride (gas) or hydrochloric acid (water solution):

NH₃ + HCl → NH₄Cl

Ammonium chloride occurs naturally in volcanic regions, forming on volcanic rocks near fume-releasing vents (fumaroles). The crystals deposit directly from the gaseous state, and tend to be short-lived, as they dissolve easily in water.

Reactions

Ammonium chloride appears to sublime upon heating. However, this process is actually decomposition into ammonia and hydrogen chloride gas.

NH₄Cl → NH₃ + HCl

Ammonium chloride reacts with a strong base, e.g. sodium hydroxide, to release ammonia gas:

NH₄Cl + NaOH → NH₃ + NaCl + H₂O

Similarly, ammonium chloride also reacts with alkali metal carbonates at elevated temperatures, giving ammonia and alkali metal chloride:

2 NH₄Cl + Na₂CO₃ → 2 NaCl + CO₂ + H₂O + 2 NH₃

A 5% by weight solution of ammonium chloride in water has a pH in the range 4.6 to 6.0.

Some of ammonium chloride's reactions with other chemicals are endothermic, for example its reaction with barium hydroxide, and its dissolving in water.

Applications

Ammonium chloride crystal(s)

The main application of ammonium chloride is as a nitrogen source in fertilizers (corresponding to 90% of the world production of ammonium chloride), e.g. chloroammonium phosphate. The main crops are rice and wheat in Asia.

Ammonium chloride was used in pyrotechnics in the 18th century but was superseded by safer and less hygroscopic chemicals. Its purpose was to provide a chlorine donor to enhance the green and blue colours from copper ions in the flame.

It had a secondary use to provide white smoke but its ready double decomposition reaction with potassium chlorate producing the highly unstable ammonium chlorate made its use very suspect.

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. For this purpose, 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.

Food

In several countries, ammonium chloride, known as sal ammoniac, is used as food additive under the E number E510, commonly as a yeast nutrient in breadmaking. It is a feed supplement for cattle and an ingredient in nutritive media for yeasts and many microorganisms.

Ammonium chloride is used to spice up dark sweets called salty liquorice (very popular in Nordic countries, especially in Finland), in baking to give cookies a very crisp texture, and in the vodka Salmiakki Koskenkorva for flavouring. In India and Pakistan, it is called "Noshader" and is used to improve the crispness of snacks such as samosas and jalebi.

In the laboratory

Ammonium chloride is used to produce low temperatures in cooling baths. Ammonium chloride solutions with ammonia are used as buffer solutions.

In paleontology, ammonium chloride vapor is deposited on fossils, where the substance forms a brilliant white, easily removed and fairly harmless and inert layer of tiny crystals. This covers up any coloration the fossil may have, and if lighted at an angle highly enhances contrast in photographic documentation of three-dimensional specimens.[1] The same technique is applied in archaeology to eliminate reflection on glass and similar specimens for photography.[2]

Flotation

Giant squid and some other large squid species maintain neutral buoyancy in seawater through an ammonium chloride solution which is found throughout their bodies and is lighter than seawater. This differs from the method of flotation used by most fish, which involves a gas-filled swim bladder. The solution tastes somewhat like salmiakki and makes giant squid unattractive for general human consumption.

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, and in cleaning products. In hair shampoo, it is used as a thickening agent in ammonium-based surfactant systems, such as ammonium lauryl sulfate. Ammonium chloride is used in the textile and leather industry in dyeing, tanning, textile printing and to luster cotton.

External links

• Calculators: surface tensions, and densities, molarities and molalities of aqueous ammonium chloride
• CDC - NIOSH Pocket Guide to Chemical Hazards