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Objective
1. To get know the uses of Ammonia.
2. To know the properties of Ammonia.
3. To explain the industrial process in the manufacture of ammonia.
4. Get know about activity to prepare ammonium fertiliser.
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Introduction to Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula NH3. It is acolourless gas with a characteristic pungent odour. Ammonia contributes significantly to the
nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers.Ammonia, either directly or indirectly, is also a building block for the synthesis of manypharmaceuticals. Although in wide use, ammonia is both caustic and hazardous. In 2006,
worldwide production was estimated at 146.5 million tonnes. It is used in commercial cleaning
products.
Ammonia, as used commercially, is often called anhydrous ammonia. This termemphasizes the absence of water in the material. Because NH3 boils at -33 C, the liquid
must be stored under high pressure or at low temperature. Its heat of vaporization is,
however, sufficiently great that NH3 can be readily handled in ordinary beakers in a
fume hood. "Household ammonia" or "ammonium hydroxide" is a solution of NH3 in
water. The strength of such solutions is measured in units of baume (density), with 26degrees baume (about 30 weight percent ammonia at 15.5 C) being the typical high
concentration commercial product. Household ammonia ranges in concentration from 5to 10 weight percent ammonia. Ammonia, NH3, is used to manufacture nitric acid,
HNO3. Nitric acid, HNO3, is then used to manufacture explosives and nitrate fertilisers.
Ammonia has a triangular pyramidal geometry, and boiling points of 77.7*C and 33.5*C. In its
pure form ammonia was prepared in 1774 by Joseph Priestly, and its composition was determined in 1785
by Claude-Louis Berthollet. Ammonia has a chemical formula of NH3, and is sp3 hybridised. Ammonia is
highly polarised, due to the electronegativity of nitrogen, and as a result, has a large dipole moment.Ammonias polarisation allows it to dissociate in water forming hydroxide and ammonium ions:
NH3 (aq) + H2O (l)NH4 (aq) + OH (aq)
Ammonia solutions are basic, due to the hydroxide ions formed in solution.
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Information
Uses of Ammonia
1. Ammonia is used in the production of liquid fertilizer solutions which consist ofammonia, ammonium nitrate, urea and aqua ammonia.It is also used by the fertilizerindustry to produce ammonium and nitrate salts.
2. Ammonia and urea are used as a source of protein in livestock feeds for ruminating
animals such as cattle, sheep and goats.Ammonia can also be used as a pre-harvest cottondefoliant, an anti-fungal agent on certain fruits and as preservative for the storage of
high-moisture corn.
3. Dissociated ammonia is used in such metal treating operations as nitriding,
carbonitriding, bright annealing, furnace brazing, sintering, sodium hydride descaling,atomic hydrogen welding and other applications where protective atmospheres are
required.
4. Ammonia is used in the manufacture of nitric acid; certain alkalies such as soda ash;
dyes; pharmaceuticals such as sulfa drugs, vitamins and cosmetics; synthetic textile fiberssuch as nylon, rayon and acrylics; and for the manufacture of certain plastics such as
phenolics and polyurethanes.
5. The petroleum industry utilizes ammonia in neutralizing the acid constituents of crude oil
and for protection of equipment from corrosion.Ammonia is used in the mining industryfor extraction of metals such as copper, nickel and molybdenum from their ores.
6. Ammonia is used in several areas of water and wastewater treatment, such as pH control,
in solution form to regenerate weak anion exchange resins, in conjunction with chlorine
to produce potable water and as an oxygen scavenger in boiler water treatment.
7. Ammonia is used in stack emission control systems to neutralize sulfur oxides from
combustion of sulfur-containing fuels, as a method of NOx control in both catalytic and
non-catalytic applications and to enhance the efficiency of electrostatic precipitators for
particulate control.
8. Ammonia is used in the rubber industry for the stabilization of natural and synthetic latex
to prevent premature coagulation.
9. Ammonia is used by the leather industry as a curing agent, as a slime and mold
preventative in tanning liquors and as a protective agent for leathers and furs in storage
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Properties of Ammonia Gas
Ammonia is a chemical consisting of one atom of nitrogen and three atoms of hydrogen. It is
designated in chemical notation as NH3. Ammonia is extremely soluble in water and is frequently used as
a water solution called aqua ammonia. Ammonia chemically combines with water to form ammonium
hydroxide. Household ammonia is a diluted water solution containing 5 to 10 percent ammonia. On theother hand, anhydrous ammonia is essentially pure (over 99 percent) ammonia. "Anhydrous" is a Greek
word meaning "without water;" therefore, anhydrous ammonia in ammonia without water.
Refrigerant grade anhydrous ammonia is a clear, colorless liquid or gas, free from visible
impurities. It is at least 99.95 percent pure ammonia. Water cannot have a content above 33 parts per
million (ppm) and oil cannot have a content above 2 ppm. Preserving the purity of the ammonia is
essential to ensure proper function of the refrigeration system.
Physical Propertiess
Anhydrous ammonia is a clear liquid that boils at a temperature of -28F. Inrefrigeration systems, the liquid is stored in closed containers under pressure. When the pressure
is released, the liquid evaporates rapidly, generally forming an invisible vapor or gas. The rapid
evaporation causes the temperature of the liquid to drop until it reaches the normal boiling point
of -28F, a similar effect occurs when water evaporates off the skin, thus cooling it. This is whyammonia is used in refrigeration systems.
Liquid anhydrous ammonia weighs less than water. About eight gallons of ammoniaweighs the same as five gallons of water.
Liquid and gas ammonia expand and contract with changes in pressure and temperature.
For example, if liquid anhydrous ammonia is in a partially filled, closed container it is heatedfrom 0F to 68F, the volume of the liquid will increase by about 10 percent. If the tank is 90
percent full at 0F, it will become 99 percent full at 68F. At the same time, the pressure in thecontainer will increase from 16 pounds per square inch (psi) to 110 psi.
Liquid ammonia will expand by 850 times when evaporating:
Anhydrous ammonia gas is considerably lighter than air and will rise in dry air. However,
because of ammonias tremendous affinity for water, it reacts immediately with the humidity in
the air and may remain close to the ground.
The odor threshold for ammonia is between 5 - 50 parts per million (ppm) of air. The
permissible exposure limit (PEL) is 50 ppm averaged over an 8 hour shift. It is recommendedthat if an employee can smell it they ought to back off and determine if they need to be using
respiratory protection.
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Summary of properties:
Boiling Point -28F
Weight per gallon of liquid at -28F 5.69 pounds
Weight per gallon of liquid at 60F 5.15 poundsSpecific gravity of the liquid (water=1) 0.619
Specific gravity of the gas (air=1) 0.588
Flammable limits in air 16-25%
Ignition temperature 1204F
Vapor pressure at 0F 16 psi
Vapor pressure at 68F 110 psi
Vapor pressure at 100F 198 psi
One cubic foot of liquid at 60F expands to 850 cubic foot of gas
Chemical Properties Anhydrous ammonia is easily absorbed by water. At 68F, about 700
volumes of vapor can be dissolved in one volume of water to make a solution containing 34 percent
ammonia by weight. Ammonia in water solution is called aqua ammonia or ammonium hydroxide.
Ammonia, especially in the presence of moisture, reacts with and corrodes copper, zinc, and
many alloys. Only iron, steel, certain rubbers and plastics, and specific nonferrous alloys resistant to
ammonia should be used for fabrications of anhydrous ammonia containers, fittings, and piping.
Ammonia will combine with mercury to form a fulminate which is an unstable explosive
compound.
Anhydrous ammonia is classified by the Department of Transportation as nonflammable. However,
ammonia vapor in high concentrations (16 to 25 percent by weight in air) will burn. It is unlikely that
such concentrations will occur except in confined spaces or in the proximity of large spills. The fire
hazard from ammonia is increased by the presence of oil or other combustible materials.
Anhydrous ammonia is an alkali
Structure of Ammonia
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Manufacture of ammonia
Ammonnia, NH3 is manufactured on a large scale in factories through the HaberProcess. There are three main stages in the manufacture of ammonia. The Haber process is
the third stage and uses a catalyst.
The three main stages in ammonia synthesis
a) Conversion of methane and steam to hydrogen and carbon monoxide
b) Removal of the carbon monoxideand the production of a mixture of hydrogen and nitrogen
c) Synthesis of ammonia in the Haber process
The process combines nitrogen gas, N2, from the air with hydrogen gas, H2, derived
mainly from natural gas to form ammonia, NH3. The two gases are mixed in the ratioof 1:3 volumes.
The hydrogen gas is obtained from methane CH4, a type of natural gas, while nitrogen
gas is obtained from air by fractional distillation of liquified air. The gas mixture is passed over
iron (catalyst) at a temperature of 450 5500C to speed up the rate of reaction and compressed
under a pressure of 200 500 atmospheres.
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THE MANUFACTURE OF AMMONIA, NH3 THROUGH HABER PROCESS
THE MANUFACTURE OF NITROGENOUS FERTILISERS
a) Ammonium Sulphate
Ammonia reacts with sulphuric acid by neutralisation to produce ammonium sulphate
2NH3+H2SO4 (NH4)2SO4
Ammonium sulphate
b) Ammonium nitrate
Ammonia reacts with nitric acid by neutralisation to produce ammonium nitrate.
The chemical compound ammonium nitrate, the nitrate of ammonia with the chemical formulaNH4NO 3, is a white crystalline solid at room temperature and standard pressure. It is commonly
used in agriculture as a high-nitrogen fertiliser, and it has also been used as an oxidizing agent in
explosives, including improvised explosive devices. It is the main component of ANFO, a verypopular explosive.
Ammonium nitrate is used in instant cold packs, as hydrating the salt is an endothermic process.
c) Urea
Urea or carbamide is an organic compound with the chemical formula (N2)2CO. The molecule
has two amine (-NH2) groups joined by a carbonyl (C=O) functional group.
The terms urea and carbamide are also used for a class of chemical compounds sharing
the same functional group RR'N-CO-NRR', namely a carbonyl group attached to two organicamine residues. Examples include carbamide peroxide, allantoin, and hydantoin. Ureas are
closely related to biurets and related in structure to amides, carbamates, diimides, carbodiimides,
and thiocarbamides.
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Preparation of Ammonium Sulphate
Ammonium sulfate is made by reacting synthetic ammonia (or by-product ammonia from
coke-ovens) with sulphuric acid
2 NH3 + H2SO4 (NH4)2SO4
A mixture of ammonia gas and water vapor is introduced into a reactor that contains a saturated
solution of ammonium sulphate and about 2 to 4% of free sulfuric acid at 60 C. Concentrated
sulfuric acid is added to keep the solution acidic, and to retain its level of free acid. The heat ofreaction keeps reactor temperature at 60 C.
Dry, powdered ammonium sulphate may be formed by spraying sulphuric acid into a reaction
chamber filled with ammonia gas. The heat of reaction evaporates all water present in the
system, forming a powdery salt.
Ammonium sulphate also is manufactured from gypsum (CaSO42H2O). Finely divided gypsum
is added to an ammonium carbonate solution. Calcium carbonate precipitates out, leaving
ammonium sulfate in the solution.
(NH4)2CO3 + CaSO4 (NH4)2SO4 + CaCO3
Ammonium sulfate occurs naturally as the rare mineral mascagnite in volcanic fumaroles and
due to coal fires on some dumps.
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DISCUSSION
The most familiar compound composed of the elements nitrogen and hydrogen, NH3. It
is formed as a result of the decomposition of most nitrogenous organic material, and itspresence is indicated by its pungent and irritating odor.
Ammonia has a wide range of industrial and agricultural applications. Examples of its use
are the production of nitric acid and ammonium salts, particularly the sulfate, nitrate, carbonate,
and chloride, and the synthesis of hundreds of organic compounds including many drugs,plastics, and dyes. Its dilute aqueous solution finds use as a household cleansing agent.
Anhydrous ammonia and ammonium salts are used as fertilizers, and anhydrous ammonia
also serves as a refrigerant, because of its high heat of vaporization and relative ease ofliquefaction.
The physical properties of ammonia are analogous to those of water and hydrogen
fluoride in that the physical constants are abnormal with respect to those of the binary hydrogen
compounds of the other members of the respective periodic families. These abnormalitiesmay be related to the association of molecules through intermolecular hydrogen bonding.
Ammonia is highly mobile in the liquid state and has a high thermal coefficient of
expansion.Most of the chemical reactions of ammonia may be classified under three chief
groups: (1) addition reactions, commonly called ammonation; (2) substitution reactions,commonly called ammonolysis; and (3) oxidation-reduction reactions.
Ammonation reactions include those in which ammonia molecules add to other
molecules or ions. Most familiar of the ammonation reactions is the reaction with water to formammonium hydroxide. The strong tendency of water and ammonia to combine is evidenced
by the very high solubility of ammonia in water. Ammonia reacts readily with strong acids toform ammonium salts. Ammonium salts of weak acids in the solid state dissociate readily
into ammonia and the free acid. Ammonation occurs with a variety of molecules capable ofacting as electron acceptors (Lewis acids), such as sulfur trioxide, sulfur dioxide, silicon
tetrafluoride, and boron trifluoride. Included among ammonation reactions is the formation
of complexes (called ammines) with many metal ions, particularly transition metal ions.Ammonolytic reactions include reactions of ammonia in which an amide group (NH2), an
imide group), or a nitride group replaces one or more atoms or groups in the reacting
molecule.
Oxidation-reduction reactions may be subdivided into those which involve a change in
the oxidation state of the nitrogen atom and those in which elemental hydrogen is liberated. Anexample of the first group is the catalytic oxidation of ammonia in air to form nitric oxide. In
the absence of a catalyst, ammonia burns in oxygen to yield nitrogen. Another example is thereduction with ammonia of hot metal oxides such as cupric oxide.
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The physical and chemical properties of liquid ammonia make it appropriate for use as a
solvent in certain types of chemical reactions. The solvent properties of liquid ammonia are,
in many ways, qualitatively intermediate between those of water and of ethyl alcohol. This isparticularly true with respect to dielectric constant; therefore, ammonia is generally superior
to ethyl alcohol as a solvent for ionic substances but is inferior to water in this respect. On
the other hand, ammonia is generally a better solvent for covalent substances than is water.
The Haber-Bosch synthesis is the major source of industrial ammonia. In a typicalprocess, water gas (CO, H2, CO2) mixed with nitrogen is passed through a scrubber cooler to
remove dust and undecomposed material. The CO2 and CO are removed by a CO2 purifier and
ammoniacal cuprous solution, respectively. The remaining H2 and N2 gases are passed over acatalyst at high pressures (up to 1000 atm or 100 megapascals) and high temperatures
(approx. 1300F or 700C). Other industrial sources of ammonia include its formation as a
by-product of the destructive distillation of coal, and its synthesis through the Cyanamidprocess. In the laboratory, ammonia is usually formed by its displacement from ammonium
salts (either dry or in solution) by strong bases. Another source is the hydrolysis of metal
nitrides.
Ammonia is commercially produced by the Haber-Bosch process, which is alsosometimes referred to as the Haber-Ammonia Process or Synthetic Ammonia Process. Fritz
Haber, the German physical chemist, created the process in 1909, and it was further developed
by Carl Bosch to make it economically viable. Both chemists won the Nobel prize for their workin this field; Haber in 1918 for its development, and Bosch in 1931 for creating high-pressure
conditions which obtained a higher yield, economically.
So how did the Haber-Bosch process come about?
At the end of the 19th century, Chilean nitrates, were the major source of nitrates at the time. It
was clear, that this source would not be able to meet future demands. It was also realised that in the event
of a war, any nation cut off from the Chilean supply, would not be able to make adequate amounts of
munitions. Germany (Habers native country) was in particular dependent on this source of nitrogen
compounds, to manufacture explosives. Following the allied block of the South American ports, thissupply was well and truly cut off. An alternative method of producing nitrates was needed. Haber
promptly got to work on the problem. In World War 1, had Haber not invented the process, Germany
would have been forced to surrender years earlier than it did. As a result the Haber-Bosch process
indirectly, cost thousands of people their lives.
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Below is a diagram of a modern ammonia production site:
HISTORY
The Romans called the ammonium chloride deposits they collected from near the Temple of
JupiterAmu n (Greek Ammon) in ancient Libya 'sal ammoniacus' (salt of Amun)
because of proximity to the nearby temple. Salts of ammonia have been known from veryearly times; thus the term Hammoniacus sal appears in the writings ofPliny, although it is
not known whether the term is identical with the more modernsal-ammoniac.
In the form of sal-ammoniac, ammonia was known to the Arabic alchemists as early as the
8th century, first mentioned by Geber (Jabir ibn Hayyan), and to the European alchemists
since the 13th century, being mentioned by Albertus Magnus. It was also used by dyers in theMiddle Ages in the form of fermented urine to alter the colour of vegetable dyes. In the 15th
century, Basilius Valentinus showed that ammonia could be obtained by the action of alkalison sal-ammoniac. At a later period, when sal-ammoniac was obtained by distilling the hoofs
and horns of oxen and neutralizing the resulting carbonate with hydrochloric acid, the name
"spirit of hartshorn" was applied to ammonia.
Gaseous ammonia was first isolated by Joseph Priestley in 1774 and was termed by him
alkaline air; however it was acquired by the alchemist Basil Valentine. Eleven years later in
1785, Claude Louis Berthollet ascertained its compositionGaseous ammonia was first isolated by Joseph Priestley in 1774 and was termed by him alkaline
air; however it was acquired by the alchemist Basil Valentine. Eleven years later in
1785, Claude Louis Berthollet ascertained its composition.
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The Haber process to produce ammonia from the nitrogen in the air was developed by
Fritz Haber and Carl Bosch in 1909 and patented in 1910. It was first used on an industrial scaleby the Germans during World War I, following the allied blockade that cut off the supply of
nitrates from Chile. The ammonia was used to produce explosives to sustain their war effort.
Prior to the advent of cheap natural gas, hydrogen as a precursor to ammonia production
was produced via the electrolysis of water. The Vemork 60 MW hydroelectric plant in Norwayconstructed in 1911 was used purely for this purpose and up until the second world war
provided the majority of Europe's ammonia.
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DISCUSSION
It was developed immediately prior to World War I by Fritz Haber and Carl Bosch,German chemists. Haber won the Nobel Prize for Chemistry in 1918 for his discoveries, while
Bosch shared a Nobel Prize with Friedrich Bergius in 1931 for his work on high-pressurechemical reactions. At first a German national secret, the chemistry and techniques behind theeffective synthesis of ammonia spread to the rest of the world in the 20s and 30s.
Ammonia is important because it is the primary ingredient in artificial fertilizers, without
which modern-day agricultural yields would be impossible. Sometimes called the "Haber
Ammonia process", the Haber-Bosch process was the first industrial chemical process tomake use of extremely high pressures (200 to 400 atmospheres). In addition to high
pressures, high temperatures (750 to 1200 degrees Fahrenheit or 400 to 650 degrees Celsius)
are used. The efficiency of the reaction is a function of pressure and temperature - greater
yields are produced at higher pressures and lower temperatures.
In the first decade of the 20th century, the artificial synthesis of nitrates was being
researched
because the world's supply of fixed nitrogen was declining rapidly relative to the demand.While nitrogen in its inactive, atmospheric gas form is very plentiful, agriculturally useful
"fixed" nitrogen compounds were harder to come by at that time in history. Agricultural
operations require liberal amounts of fixed nitrogen to produce good yields. At the turn of the
century, all the world's developed countries were required to mass import nitrates from thelargest available source - Chilean saltpeter (NaNO3). Many scientists started worrying about
the declining supply of nitrogen compounds.
The Haber-Bosch process provided a solution to the shortage of fixed nitrogen. Using
extremely high pressures and a catalyst composed mostly of iron, critical chemicals used inboth the production of fertilizers and explosives were made highly accessible to German
industry, making it possible for them to continue fighting WWI effectively. As the Haber-
Bosch process branched out in global use, it became the primary procedure responsible forthe production of fertilizer to feed the world's population. Without it, billions of people might
not exist. Today, the Haber-Bosch process is used to produce more than 500 million tons (453
billion kilograms) of artificial fertilizer per year; roughly 1% of the world's energy is used forit, and it sustains about 40% of our planetary population.
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Ammonia, chemicalsymbol NH3, can take the form of a strong smelling liquid or gas. Most
popularly, consumer and commercial products use the alkaline substance to clean grime or
fertilize crops. Even in low concentrations, inhaling ammonia or getting the solution on your skincan cause burning, fainting, or death, so always use caution when handling this chemical.
Ammonia has one nitrogenatom and threehydrogen atoms tightly bonded. A tiny amount of
ammonia forms when organic matter decomposes, so the gas can be found naturally in our
atmosphere. Most of the ammonia used is produced through artificial means, however, bybonding the four atoms together by sheer force. Then the gas can be pressurized to form a liquid
for easy distribution to manufacturing plants.
As a gas, ammonia is lighter than air, so it won't pool indoors like other dangerous gases, such as
propane. While it has a very pungent, distinctive odor, it's clear and difficult to combust unlesshighly concentrated. This makes ammonia safer than other chemicals for household use, as most
people will recognize the smell and leave a toxic area to prevent fainting.
Since ammonia gets easily incorporated into water as a solution, it's used in many cleaners.
Many window sprays, oven foam, toilet bowl cleansers, wax removers, and other householdcleaners contain around 5-10% ammonia. Different types of cleaners should never be mixed in
the same application. For example, ammonia and bleach form a very dangerous gas, called
chloramine, that shouldn't be inhaled.
Commercial cleansers, with 25-30% ammonia, are extremely dangerous due to their corrosivity.Under careful oversight, liquid ammonia is also used to etch metal like aluminum and copper,
refrigerate rooms or trucks, and dissolve other elements inchemistry labs. Most of the ammonia
we produce goes to fertilizing crops by providing absorbable nitrogen to plants. Manufacturers of
plastics, pesticides, and dyes use the liquid at some point in their synthesizing process.
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Reference
http://www.chm.bris.ac.uk/webprojects2001/prime/
http://en.wikipedia.org/wiki/Ammonia
http://www.osha.gov/SLTC/etools/ammonia_refrigeration/ammonia/index.html
http://www.rmtech.net/uses_of_ammonia.htm
http://www.hillakomem.com/tag/ammonium-carbamate
http://www.chm.bris.ac.uk/webprojects2001/prime/http://en.wikipedia.org/wiki/Ammoniahttp://www.rmtech.net/uses_of_ammonia.htmhttp://www.hillakomem.com/tag/ammonium-carbamatehttp://www.chm.bris.ac.uk/webprojects2001/prime/http://en.wikipedia.org/wiki/Ammoniahttp://www.rmtech.net/uses_of_ammonia.htmhttp://www.hillakomem.com/tag/ammonium-carbamate