Ammonium chloride

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Ammonium chloride
Unit cell of ammonium chloride
Powder of ammonium chloride
Identifiers
CAS number12125-02-9 YesY
ChemSpider23807 YesY
UNII01Q9PC255D YesY
EC number235-186-4
KEGGD01139 YesY
ChEBICHEBI:31206 YesY
RTECS numberBP4550000
ATC codeB05XA04,G04BA01
Jmol-3D imagesImage 1
Properties
Molecular formulaH4ClN
Molar mass53.49 g mol−1
AppearanceWhite solid, hygroscopic
OdorOdorless
Density1.5274 g/cm3[1]
Melting point338 °C (640 °F; 611 K) decomposes, sublimes
Boiling point520 °C (968 °F; 793 K)
Sublimation conditionsSublimes at 337.6 °C[2]
ΔsublHo = 176.1 kJ/mol[3]
Solubility in water244 g/L (−15 °C)
294 g/L (0 °C)
391.8 g/L (25 °C)
454.4 g/L (40 °C)
740.8 g/L (100 °C)[4]
Solubility product, Ksp30.9 (395 g/L)[5]
SolubilitySoluble in liquid ammonia, acetone, hydrazine, alcohol
Insoluble in diethyl ether, ethyl acetate[2]
Solubility in methanol3.2 g/100 g (17 °C)
3.35 g/100 g (19 °C)
3.54 g/100 g (25 °C)[2]
Solubility in ethanol6 g/L (19 °C)[1]
Solubility in glycerol97 g/kg[2]
Solubility in sulfur dioxide0.09 g/kg (0 °C)
0.031 g/kg (25 °C)[2]
Solubility in acetic acid0.67 g/kg (16.6 °C)[2]
Vapor pressure133.3 Pa (160.4 °C)[6]
6.5 kPa (250 °C)
33.5 kPa (300 °C)[1]
Acidity (pKa)9.24
Refractive index (nD)1.642 (20 °C)[2]
Thermochemistry
Specific
heat capacity
C
84.1 J/mol·K[1]
Std molar
entropy
So298
94.56 J/mol·K[1]
Std enthalpy of
formation
ΔfHo298
−314.43 kJ/mol[1]
Gibbs free energy ΔG−202.97 kJ/mol[1]
Hazards
MSDSICSC 1051
GHS pictogramsThe exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)[6]
GHS signal wordWarning
GHS hazard statementsH302, H319[6]
GHS precautionary statementsP305+351+338[6]
EU Index017-014-00-8
EU classificationHarmful Xn Irritant Xi
R-phrasesR22, R36
S-phrases(S2), S22
NFPA 704
Flash pointNon-flammable
LD501650 mg/kg (rats, oral)
Related compounds
Other anionsAmmonium fluoride
Ammonium bromide
Ammonium iodide
Other cationsSodium chloride
Potassium chloride
Hydroxylammonium chloride
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references
 
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Ammonium chloride
Unit cell of ammonium chloride
Powder of ammonium chloride
Identifiers
CAS number12125-02-9 YesY
ChemSpider23807 YesY
UNII01Q9PC255D YesY
EC number235-186-4
KEGGD01139 YesY
ChEBICHEBI:31206 YesY
RTECS numberBP4550000
ATC codeB05XA04,G04BA01
Jmol-3D imagesImage 1
Properties
Molecular formulaH4ClN
Molar mass53.49 g mol−1
AppearanceWhite solid, hygroscopic
OdorOdorless
Density1.5274 g/cm3[1]
Melting point338 °C (640 °F; 611 K) decomposes, sublimes
Boiling point520 °C (968 °F; 793 K)
Sublimation conditionsSublimes at 337.6 °C[2]
ΔsublHo = 176.1 kJ/mol[3]
Solubility in water244 g/L (−15 °C)
294 g/L (0 °C)
391.8 g/L (25 °C)
454.4 g/L (40 °C)
740.8 g/L (100 °C)[4]
Solubility product, Ksp30.9 (395 g/L)[5]
SolubilitySoluble in liquid ammonia, acetone, hydrazine, alcohol
Insoluble in diethyl ether, ethyl acetate[2]
Solubility in methanol3.2 g/100 g (17 °C)
3.35 g/100 g (19 °C)
3.54 g/100 g (25 °C)[2]
Solubility in ethanol6 g/L (19 °C)[1]
Solubility in glycerol97 g/kg[2]
Solubility in sulfur dioxide0.09 g/kg (0 °C)
0.031 g/kg (25 °C)[2]
Solubility in acetic acid0.67 g/kg (16.6 °C)[2]
Vapor pressure133.3 Pa (160.4 °C)[6]
6.5 kPa (250 °C)
33.5 kPa (300 °C)[1]
Acidity (pKa)9.24
Refractive index (nD)1.642 (20 °C)[2]
Thermochemistry
Specific
heat capacity
C
84.1 J/mol·K[1]
Std molar
entropy
So298
94.56 J/mol·K[1]
Std enthalpy of
formation
ΔfHo298
−314.43 kJ/mol[1]
Gibbs free energy ΔG−202.97 kJ/mol[1]
Hazards
MSDSICSC 1051
GHS pictogramsThe exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)[6]
GHS signal wordWarning
GHS hazard statementsH302, H319[6]
GHS precautionary statementsP305+351+338[6]
EU Index017-014-00-8
EU classificationHarmful Xn Irritant Xi
R-phrasesR22, R36
S-phrases(S2), S22
NFPA 704
Flash pointNon-flammable
LD501650 mg/kg (rats, oral)
Related compounds
Other anionsAmmonium fluoride
Ammonium bromide
Ammonium iodide
Other cationsSodium chloride
Potassium chloride
Hydroxylammonium chloride
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
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[edit]

It is a product of the Solvay process used to produce sodium carbonate.[3]

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):[3]

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.[7]

Reactions[edit]

Ammonium chloride appears to sublime upon heating. However, this process is actually decomposition into ammonia and hydrogen chloride gas.[3]

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.[8]

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

Applications[edit]

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.[9]

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.[10][11][12]

Metalwork[edit]

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[edit]

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[edit]

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, 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[edit]

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 precipitated 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[edit]

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[edit]

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.

References[edit]

  1. ^ a b c d e f g Pradyot, Patnaik (2003). Handbook of Inorganic Chemicals. The McGraw-Hill Companies, Inc. ISBN 0-07-049439-8. 
  2. ^ a b c d e f g http://chemister.ru/Database/properties-en.php?dbid=1&id=371
  3. ^ a b c d Wiberg, Egon; Wiberg, Nils (2001). Inorganic Chemistry (illustrated ed.). Academic Press. p. 614. ISBN 0-12-352651-5. 
  4. ^ Seidell, Atherton; Linke, William F. (1919). Solubilities of Inorganic and Organic Compounds (2nd ed.). D. Van Nostrand Company. 
    Results here are multiplied by water's density at temperature of solution for unit conversion.
  5. ^ "Solubility Products of Selected Compounds". http://www.saltlakemetals.com. Salt Lake Metals. Retrieved 2014-06-11. 
  6. ^ a b c d Sigma-Aldrich Co., Ammonium chloride. Retrieved on 2014-06-11.
  7. ^ Rowley, Steven P. (2011). General Chemistry I Laboratory Manual (Second ed.). Kendall Hunt. ISBN 978-0-7575-8942-3. 
  8. ^ Dr. K. G. Bothara (7 October 2008). Inorganic Pharmaceutical Chemistry. Pragati Books Pvt. Ltd. pp. 13–. ISBN 978-81-85790-05-3. Retrieved 12 October 2011. 
  9. ^ Karl-Heinz Zapp "Ammonium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry 2012, Wiley-VCH, Weinheim. doi:10.1002/14356007.a02_243
  10. ^ John A. Conkling; Christopher J. Mocella (2010). Chemistry of Pyrotechnics (2nd ed.). CRC Press. ISBN 978-1574447408. 
  11. ^ Tenney L Davis (2012). Chemistry of Powder and Explosives. Angriff Press. ISBN 978-0945001171. 
  12. ^ K. L. Kosanke; B. J. Kosanke; Barry T. Sturman; Robert M. Winokur (2012). Encyclopedic Dictionary of Pyrotechnics (and Related Subjects). Journal of Pyrotechnics. ISBN 978-1889526195. 

External links[edit]