Ammonium chloride

Ammonium chloride (NH4C1, density 1.52) is a white crystalline solid that decomposes at 350°C and sublimes at 520°C under controlled conditions. It is also known as sal ammoniac and is soluble in water and in aqueous solutions of ammonia it is slightly soluble in methyl alcohol. 

Ammonium chloride is produced by neutralizing hydrochloric acid (HC1) with ammonia gas or with liquid ammonium hydroxide, and evaporating the excess water, followed by drying, crystallizing, and screening operations. 

Ammonium chloride can also be produced in the gaseous phase by reacting hydrogen chloride gas with ammonia. 

Ammonium chloride is used as an ingredient of dry cell batteries, as a soldering flux, as a processing ingredient in textile printing and hide tanning, and as a starting material for the manufacture of other ammonium chemicals. 

Ammonium chloride (uh-MOH-ni-um KLOR-ide) occurs as odorless white crystals with a cool, salt-like taste. The compound is of interest to historians of chemistry as being one of the first chemicals mentioned by ancient scholars and the first compound of ammonia to have been discovered. For example, the Roman philosopher Pliny the Elder (23-79 ce) wrote about a substance he called hammoniacus sal that appears to have been ammonium chloride. The problem is that various authorities used the term Aal ammoniac for a variety of materials that were clearly different from each other. No one really knew the compound s actual chemical composition until 1700, when it was discovered by the French botanist Joseph Tournefort (1656-1708). In any case, Aal ammoniac was an important raw material in early industrial operations, including primarily dyeing and metallurgical operations. 

Sal ammoniac is also the name of the mineral form of ammonium chloride. The mineral occurs only rarely in 

Ammonium chloride. White atoms are hydrogen blue atom is nitrogen and yellow atom is chlorine, publishers 

Sal ammoniac was an important substance in the study of alchemy. The goals and methods of alchemy changed considerably over the period from about the twelfth century to about the sixteenth century and were somewhat different 

Ammonium chloride has a wide variety of commercial uses. One of the best known uses is in dry cell batteries. Dry cell batteries consist of three parts the anode (the metal bottom of the battery), the cathode (the metal knob at the top of the battery), and the electrolyte (a moist solid material that makes up the body of the battery). Electrons produced in a chemical reaction within the battery flow out of the cathode, through an external circuit (the device to which the battery is attached), hack into the battery through the anode, and back to the cathode through the electrolyte. The electrolyte in a dry cell battery consists of a pasty mixture of ammonium chloride with water. 

Colorless cubic crystals or white granular powder saline taste odorless hygroscopic does not melt but sublimes on heating at 340°C vapor pressure 48.75 torr at 250°C and 251.2 torr at 300°C density 1.5274 g/cm at 25°C refractive index 1.642 readily dissolves in water, solubihty 229 g and 271 g/L solution at 0°C and 20°C, respectively solubdity lowered by alkah metal chlorides and HCl dissolution lowers the temperature of the solution sparingly soluble in alcohols (6 g/L at 19°C) and soluble in hquid NH3 insoluble in acetone and ether. 

Ammonium chloride is produced as a by-product in the Solvay process for manufacture of sodium carbonate  

NaHCOs precipitate is filtered out of solution while NH4CI is obtained by crystallization followed by washing and drying. Ammonium chloride also is produced from spent calcium chloride liquor obtained in ammonia-soda process  

It also is made by heating a mixture of slight excess of NaCl solution with ammonium sulfate. The filtrate containing NH4CI is concentrated and cooled. NH4CI crystallizes  

NH4CI is acidic in aqueous solution the pH of 1%, 3%, and 10% solution at 25°C are 5.5, 5.1 and 5.0, respectively. (Merck 1996. The Merck Index, 12th ed. Rahway, NJ Merck Co.) It loses ammonia and becomes more acidic on prolonged exposure or storage. It reacts with iron, copper, nickel and other metals and some of their alloys such as bronze and brass. It reacts with alkalies forming NH3. 

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CH2=CHC = CCH = CH2. a colourless liquid which turns yellow on exposure to the air it has a distinct garlic-like odour b.p. 83-5°C. Manufactured by the controlled, low-temperature polymerization of acetylene in the presence of an aqueous solution of copper(I) and ammonium chlorides. It is very dangerous to handle, as it absorbs oxygen from the air to give an explosive peroxide. When heated in an inert atmosphere, it polymerizes to form first a drying oil and finally a hard, brittle insoluble resin. Reacts with chlorine to give a mixture of chlorinated products used as drying oils and plastics. 

These water streams contain mainly dissolved salts ammonium chloride and sulfide, sodium chloride, traces of cyanide, phenols for water coming from catalytic and thermal cracking operations. 

The calcium oxide so produced is slaked to give a suspension of calcium hydroxide and this is heated with the filtrate from the carbonator which contains ammonium chloride ... 

Hence, if chlorine is passed into a cold suspension (in hydrochloric acid) of lead(II) chloride, lead(IV) chloride is formed. Addition of ammonium chloride gives the complex salt ammonium hexachloro-plumbate(lV) as a yellow precipitate ... 

It is best prepared by heating an intimate mixture of solid ammonium chloride and quicklime ... 

Aqueous ammonia can also behave as a weak base giving hydroxide ions in solution. However, addition of aqueous ammonia to a solution of a cation which normally forms an insoluble hydroxide may not always precipitate the latter, because (a) the ammonia may form a complex ammine with the cation and (b) because the concentration of hydroxide ions available in aqueous ammonia may be insufficient to exceed the solubility product of the cation hydroxide. Effects (a) and (b) may operate simultaneously. The hydroxyl ion concentration of aqueous ammonia can be further reduced by the addition of ammonium chloride hence this mixture can be used to precipitate the hydroxides of, for example, aluminium and chrom-ium(III) but not nickel(II) or cobalt(II). 

When chlorine is passed into aqueous ammonia, ammonium chloride and nitrogen are formed. If, however, sodium chloratefi) (hypochlorite) is used instead of chlorine, chloramine is first formed ... 

Uses of hydrogen chloride—Hydrogen chloride is sometimes used in the preparation of an ester, for example ethyl benzoate, where it acts as both an acid catalyst and a dehydrating agent. Hydrochloric acid is used primarily to produce chlorides, for example ammonium chloride. It is extensively used in the manufacture of anilme dyes, and for cleaning iron before galvanising and tin-plating. 

Addition of sulphide ion to a solution of a zinc salt containing ammonia and ammonium chloride gives a white precipitate of zinc sulphide. 

A certain amount of hydrolysis of the original acetamide to acid and ammonia always occurs, and the final amine always contains traces of ammonia. This is separated by extracting the mixed anhydrous hydrochlorides with absolute ethanol, which dissolves the amine hydrochloride but not the ammonium chloride filtration of the hot ethanolic extract removes the ammonium chloride, whilst the amine hydrochloride crystallises readily from the filtrate on cooling. 

Caution.—If the ethanol used to extract the methylamine hydrochloride is not absolute, i.e., if it contains traces of water, considerably less than the above suggested quantity will be required for the extraction, because the solubility of the hydrochloride will be markedly increased by the water present. The recrystallised material will now, however, contain traces of ammonium chloride. 

The glycine so formed has to be separated from the ammonium chloride, and... 

The glycine so obtained is almost pure. To remove traces of ammonium chloride, however, dissolve the glycine in 30 ml. of water, and then reprecipitate by the addition of 200 ml. of methanol. Cool the product in ice-water with stirring, and then... 

The method of hydrolysis depends on the nature of the product. It is usually sufficient to add dilute sulphuric acid to the ethereal solution and to shake thoroughly, when the magnesium enters the aqueous solution, whilst the organic compound remains in the ether. Alternatively, however, the ethereal solution may be poured on to ice and water, and then treated with dilute sulphuric acid. Should the product be affected by this acid, the hydrolysis can be carried out with an aqueous solution of ammonium chloride. In the following examples the hydrolysis is usually shown as a simple double decomposition... 

D) Bmzylamides. Many acids when heated directly with benzyl-amine in the presence of ammonium chloride as a catalyst give the... 

Example. Heat together under reflux 0-5 g. of citric acid, 3 ml. of benzylamine and 015 g. of ammonium chloride for i hour. Cool, shake with about 10 ml. of water and filter off the solid. Recrystallise from ethanol small white crystals m.p. 170 . (M.ps., pp. 543-545 )... 

Alternatively, the bulk of the platinum in the aqueous residues can be precipitated by ammonium chloride as ammonium chloroplatinate, the latter filtered off, and the filtrate evaporated to dryness. The chloroplatinate and the residue from the evaporation are then ignited. 

The contents of B, which act as a control, are treated with mercuric chloride in order to inhibit the action of the enzyme, and then 10 ml. of urease solution are added. The solution is diluted with water and ammonium chloride added (in order to balance the ammonium chloride subsequently formed in A). Meth) l-red is then added and the solution is titrated with Mj 10 HCl from a second burette B until a bright red colour is obtained. 

Meanwhile add 4 drops of methyl-red and 1 ml. of 10% ammonium chloride solution to B. The colour will normally be yellow if so, add A//10 HCl from Bh drop by drop, until a red colour is just obtained. 

Dilute hydrochloric or sulphuric acid finds application in the extraction of basic substances from mixtures or in the removal of basic impurities. The dilute acid converts the base e.g., ammonia, amines, etc.) into a water-soluble salt e.g., ammonium chloride, amine hydrochloride). Thus traces of aniline may be separated from impure acetanilide by shaking with dilute hydrochloric acid the aniline is converted into the soluble salt (aniline hydrochloride) whilst the acetanilide remains unaffected. 

Hydrogen chloride. Method 1 from concentrated sulphuric acid and fused ammonium chloride). The most convenient procedure is to allow concentrated sulphuric acid to react with lumps of fused ammonium chloride in a Kipp s apparatus. The gas may be dried by passage through a wash bottle containing concentrated sulphuric acid the latter should be followed by an empty wash bottle or flask as a precaution against sucking back of the contents of the reaction vessel. 

This preparation illustrates the preparation of a liquid hydrocarbon from a Grignard reagent. The Grignard reagent from n-hexyl bromide may be decomposed either with dilute sulphuric acid or with solid ammonium chloride the latter gives a somewhat better 3neld. 

Now run in a solution of 52 g. (53-5 ml.) of pure diethyl carbonate (1) in 70 ml. of anhydrous ether, with rapid stirring, over a period of about one hour. A vigorous reaction sets in and the ether refluxes continually. When the diethyl carbonate has been added, heat the flask on a water bath with stirring for another hour. Pour the reaction mixture, with frequent shaking, into a 2 litre round-bottomed flask containing 500 g. of crushed ice and a solution of 100 g. of ammonium chloride in 200 ml. of water. Transfer to a separatory funnel, remove the ether layer, and extract the aqueous solution with two 176 ml. portions of ether. Dry... 

H-Benzylamides of acids from esters. Esters are converted into the A-benzylamides of the corresponding acids by heating with benzylamine in the presence of a httle ammonium chloride as catalyst ... 

Reflux a mixture of 1 g. of the ester, 3 ml. of benzylamine and 0 1 g. of powdered ammonium chloride for 1 hour in a Pyrex test-tube fltted with a short condenser. Wash the cold reaction mixture with water to remove the excess of benzylamine. If the product does not crystallise, stir it with a httle water containing a drop or two of dilute hydrochloric acid. If crystallisation does not result, some unchanged ester may be present ... 

When ammonium chloride is heated to a higher temperature (160°) with a large excess of anhydrous formaldehyde (as paraformaldehyde), trimethyl-amine hydrochloride (trimethylammonium chloride) may be obtained ... 

Mix 100 g. of ammonium chloride and 266 g. of paraformaldehyde in a 1-litre rovmd-bottomed flask fitted with a long reflux condenser containing a wide inner tube (ca. 2 cm. diameter) the last-named is to avoid clogging the condenser by paraformaldehyde which may sublime. Immerse the flask in an oil bath and gradually raise the temperature. The mixture at the bottom of the flask liquefies between 85° and 105° and a vigorous evolution of carbon dioxide commences at once remove the burner beneath the oil bath and if the reaction becomes too violent remove... 

The absence of ammonium chloride and methylamine hydrochloride may be shown by the complete solubility of the product in chloroform. 

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