Class of 2014 IB Chem

hydrogen bonding

plants are not able to assimilate gaseous nitrogen unless it is converted to ammonia or some other form.

Ammonia is one of the most widely used compounds in the United States, serving as a raw material for the production of many important compounds and as a nutrient for the growth of crops.

An especially important example involves Rhizobium bacteria in root nodules of leguminous plants, and is the basis for the common agricultural practice of growing legumes in rotation with other crops to enrich fields with available nitrogen.

One reason that the war lasted until late 1918 was German use of the Haber- Bosch process to make ammonia and the Ostwald Process to convert ammonia into nitric acid and nitrates.

British and American efforts to produce ammonia using the Haber-Bosch Process during World War I failed even though several attempts were made and patents for the process were available. The failure was due to a lack of knowledge and ability in building and maintaining the high pressure equipment needed to carry out the reaction and a lack of knowledge about the chemistry of the catalysts needed. The German patents omitted many vital technical details, particularly those concerning the preparation of the required catalysts.

increase the amount and availability of explosives produced but they did not substantially change the techniques and basic chemical reactions that Nobel and others developed in the late 19th century. More importantly, the Haber-Bosch Process has changed the way nitrogen fertilizers are produced and used and has increased the availability and use of fertilizers. It is an important part of the "Green Revolution" of the 20th century.

About 90 percent of all the ammonia used in the United States goes to the production of fertilizers.

The Haber-Bosch process remains the most common form of ammonia production in many countries, including the United States.

Ammonia is used in a variety of forms as a fertilizer.

In addition to its use in the manufacture of fertilizers and explosives, smaller amounts of ammonia are used: As a refrigerant; In the manufacture of plastics; As a raw material in the manufacture of other nitrogen-containing chemicals; In the production of dyes; As a rocket fuel; For the neutralization of acids during the refining of petroleum; In order to produce specialized types of steel; and As a nutrient in yeast cultures in food processing operations.

The next largest use of ammonia is in the synthesis of nitric acid (HNO3). In a process developed by the German chemist Wilhelm Ostwald (1853–1932), ammonia, oxygen, and water are reacted together in a series of steps that results in the formation of nitric acid. Nitric acid, the thirteenth most important chemical in the United States in terms of productions, has a number of important uses, including the manufacture of explosives. Like the Haber-Bosch process, the Ostwald process contributed to the success experienced by Germany during World War I.

Both gaseous and liquid ammonia pose moderate health hazards to those who come into contact with them. For example, farmers who handle liquid ammonia risk the possibility of painful blistering of the skin or damage to the mucous membranes if they come into contact with the ferilizer. Ammonia fumes can irritate the mouth, nose, and throat, causing coughing and gagging responses. Higher levels of exposure may irritate the lungs, resulting in shortness of breath and producing headaches, nausea, and vomiting. Very high exposures can cause a buildup of fluid in the lungs that can result in death. Since ammonia is a common ingredient of many household products, everyone should be aware of its health risks, although the threat posed by such products is, in fact, very small.

His wife (also a chemist) objected so much to his 'immoral' role that she committed suicide by shooting herself in his living room

He remained there in self-imposed exile until his death some years later.

the chemistry of ammonia synthesis was being explored by the German chemists Fritz Haber and Walther Bosch who found that it was possible to produce ammonia from nitrogen and hydrogen by the process:

Holland says the nitrides formed in solution could be useful in making pharmaceuticals and other products.

Increasing the pressure brings the molecules closer together. In this particular instance, it will increase their chances of hitting and sticking to the surface of the catalyst where they can react. The higher the pressure the better in terms of the rate of a gas reaction.

You have to build extremely strong pipes and containment vessels to withstand the very high pressure. That increases your capital costs when the plant is built. High pressures cost a lot to produce and maintain. That means that the running costs of your plant are very high.

Recycling

This trade

the lack of fixed nitrogen is often the limiting factor in an ecosystem or for crops.

the process and Carl Bosch was charged with upscaling it to factory size, a feat he managed by 1913.

Between 500 and 600 were killed and 2000 injured.

We convert more N2 gas into fixed reactive forms than all the Earth's processes combined. Synthetic nitrogen fertilizer production, vehicle exhaust emissions and e

Through the 1800's, heavily populated countries in Europe such as Germany and Britain used guano from islands off the coast of Peru and salt petre from Chile as a source of natural nitrogen fertilizer

For a brief time the first factory turned out fertilizer. With onset of WW1 Germany needed munitions for its war effort. The factory was seconded to munitions and is credited or blamed with greatly prolonging WW1 and making WW2 possible.

It wasn't until the 1950's, after the first and second world wars, that the Haber process really started to affect farming. Ammonia stocks, diverted in wartime to make bombs and bullets, started being used to produce the synthetic nitrogen fertilizers used everywhere today.

Usually, the heat is used to raise high pressure steam to run turbines for compressors. Even the relatively low grade heat can be used to reheat process gas to power an expansion turbine.

Dual pressure systems, operating the burner section at medium pressure and the absorption section at high pressure, to take best advantage of the natural conversion efficiencies of the two stages, have also been commercially successful.

an energy cost.

Nowadays, pollution control regulations in many countries stipulate a maximum of 200 ppmv total nitrogen oxides in tail gas, and this can only be achieved directly in a high pressure absorption section. Developments in platinum catalysts

catalysts used today is their similarity to those used when the ammonia oxidation route was conceived. In 1909, Karl Kaiser's patent indicated the use of a woven gauze made from 0.060 mm (60 micron) wire with 1204 mesh per cm 2. Today, whichever supplier is used, the majority of nitric acid plants use gauzes made from 0.076 or 0.060 mm wire at 1024 mesh to the square centimetre.

contact times in the order of seconds are necessary to ensure that every ammonia molecule striking the catalyst is oxidized to nitric oxide, and low pressure drops across the catalyst are needed to maintain the fast gas flows. The catalyst must be capable of withstanding these high gas velocities and also significant turbulence at high temperature, for periods up to two months in high pressure plants, and longer for medium pressure facilities.

The stated advantages of the knitted gauze are greater exposed surface area, giving increased conversion efficiency and lighter gauzes of the same size, because the cross-over points give greater accessibility to gas impingement.

The first "getter gauzes" were introduced in 1968 by Degussa, the German gold-and-silver refiners. Not surprisingly, this gauze was made from an alloy containing 80% palladium and 20% gold. The catchment principle is that platinum vapour displaces the palladium on the catchment gauze, so that the palladium - which is about a quarter the value of platinum - is lost but more valuable platinum is caught for subsequent recovery. The gauze could be installed immediately after the catalyst assembly, and the presence of gold was required to enhance the mechanical strength of the palladium wire. The drawback with this very effective catchment system is that the price of gold was not only high in the late 1960s but it is even higher today, and from the start the quest was on to develop a workable system comprised of cheaper materials. Over the years, the 20% gold was reduced to 10%, and more recently has been eliminated altogether with the development of goldfree palladium alloys, containing such components as chromium, manganese, boron and carbon. Degussa has also recently announced the development of a catchment gauze made from palladium coated nickel wire (Fig. 4). Getter gauze assemblies nowadays consist of two or more gauzes separated from the catalyst only by a heat resistant mesh. They recover platinum and rhodium and, whereas in the early 1980s they were capable of recovering 7585% of primary platinum losses, recovery levels of more than 85% are claimed today, but lower recoveries are to be expected in high pressure plants. Of the specific proprietary systems, Johnson Matthey's PLUS PAC hinged, folded gold-free gauze for easy installation was introduced around 1983, while Engelhard's MTL system - originally launched in the 1970s as Palladium Plus - has very recently been revamped to what the company describes as a unique low pressure drop design. Known as LPMTL, the new system is said to reduce pressure drop effects by as much as 70%. Interestingly Degussa, the original developer of palladium catchment gauzes, has licensed gold-free "getter" gauzes from Engelhard. Dimensions of catchment gauzes have now been thoroughly investigated in regard to their gas flow characteristics, and so further improvements may be less spectacular, but the search for cheaper materials continues.

Between the catalytic combustion section and the oxidation/absorption section of the nitric acid process, the gas stream needs t6 be efficiently cooled, and this presents an opportunity to recover heat in waste heat boilers and heat exchangers. There are two major considerations for the designer: first, in certain areas of the flow sheet, the gas stream must not be allowed to go below the dew point because of the risk of corrosion; and second the higher the grade of heat recovered, the more valuable it is. The objective is maximum heat recovery at lowest capital cost.

Holland points out that the catalyst used in Haber-Bosch is considerably less expensive than what was used by his team.

Ammonium hydroxide exhibits the characteristics of a weak base, turning litmus paper blue, and neutralizing acids with the formation of ammonium salts.

In liquid or frozen ammonia, the molecules attract one another through sharing a hydrogen atom between one molecule and the next, called hydrogen bonding. In this attraction, called association, compounds apparently containing free electrons can be obtained by treating sodium/ammonia solutions with complexing agents.

When dry, this substance is so sensitive that the lightest touch will cause it to explode with a crackling sound and a puff of purple iodine vapor.