The Haber Process In WWI

The Process Reactants = N2(g) + 3H2(g) Products = 2NH3(g), ΔHo = -92.4 kJ/mol Process is carried out at 150 - 250 atmospheres (atm) and between 300 and 550 °C On each pass only about 15% conversion occurs, but any unreacted gases are recycled, so that eventually an overall conversion of 98% can be achieved.

Preparing Reactants Hydrogen Processed by taking methane (CH4(g)) and reacting it with steam (H2O(g)) Products are carbon dioxide (CO2(g)) and hydrogen (H2(g)). Nitrogen (N2(g)) is obtained from the air by fractional distillation, because the air is made up of 80% nitrogen.

Fractional Distillation Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point. Generally the component parts boil at less than 25°C from each other under a pressure of one atmosphere (atm). If the difference in boiling points is greater than 25°C, a simple distillation is used.

Conditions As the temperature increases, the equilibrium is shifted and hence, the constant drops dramatically according to the van't Hoff equation. Thus one might suppose that a low temperature is to be used and some other means to increase rate. However, the catalyst itself requires a temperature of at least 400 °C to be efficient.

Conditions Cnt. Pressure is the obvious choice to favour the forward reaction because there are 4 moles of reactant for every 2 moles of product, and the pressure used (around 200 atm) alters the equilibrium concentrations to give a profitable yield. Economically, though, pressure is an expensive commodity. Pipes and reaction vessels need to be strengthened, valves more rigorous, and there are safety considerations of working at 200 atm. In addition, running pumps and compressors uses considerable energy. The compromise used gives a single pass yield of around 15%.

Catalyst The catalyst has no effect on the position of equilibrium, rather, it provides an alternative pathway with lower activation energy and hence increases the reaction rate, while remaining chemically unchanged at the end of the reaction. The first Haber–Bosch reaction chambers used osmium and uranium catalysts. However, today a much less expensive iron catalyst is used almost exclusively.

Beginings The process was first patented by Fritz Haber. In 1910 Carl Bosch, while working for chemical company BASF, successfully commercialized the process and secured further patents. Haber and Bosch were later awarded Nobel prizes, in 1918 and 1931 respectively, for their work in overcoming the chemical and engineering problems posed by the use of large-scale high-pressure technology. Fritz Haber Carl Bosch

WWI Ammonia was first manufactured using the Haber process on an industrial scale in Germany during World War I to meet the high demand for ammonium nitrate (for use in explosives) at a time when supply of Chile saltpetre from Chile could not be guaranteed 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. It has been suggested that without this process, Germany would not have started the war. 50 lbs Ammonium Nitrate

Chilean Saltpetre "Chile saltpeter“-Sodium nitrate is the chemical compound with the formula NaNO3. Sodium nitrate is used as an ingredient in fertilizers, explosives, and in solid rocket propellants. Many deposits were mined for over a century, until the 1940s, when its value declined dramatically in the first decades of the twentieth century (Due to Haber Process). Germany could not get Chile saltpetre from Chile because this industry was then almost 100% in British hands.

Begining of the War World War I Began in 1914 with the assassination of the Archduke of Austria Hungary Ferdinand. The assassination triggered a chain of declarations of war between the members of the Triple Entente (England, France, and Russia) and the Triple Alliance (Austria-Hungary, Germany, Italy). The Triple Entente’s naval superiority allowed the allies to effectively blockade the trade of the Triple Alliance (mainly Germany). Following the allied blockade of the South American ports, the supply of Saltpetre was well and truly cut off. This blockade was a major contributing factor in the Germans use of unrestricted submarine warfare.

New Developments Big Bertha Artillery: These were the new and upgraded versions of cannons. Never in the history of man, where there so many cannons used in one war alone. For four years the British had been using artillery and firing 170 million shells in that time. Germany had a plan up their sleeve. For years, German scientists were developing the biggest artillery ever known. It was call the ‘Big Bertha’. Big Bertha was so powerful it could fire at the heart of Paris from 120 kilometers away. The cannons weren’t the only things that had been improved. The shells were upgraded as well. Instead of ordinary shells, new High-explosive shells were developed. The Shells were thin casings and were filled with tiny lead pellets. This was so effective, that artillery fire killed hundreds and thousands of men. Big Bertha

High-Explosives Ammonal An explosive made up of ammonium nitrate, trinitrotoluene, and aluminium powder mixed in a ratio of roughly 22:67:11 The ammonium nitrate functions as an oxidizer and aluminium as a power enhancer. To some extent the aluminium makes it more sensitive to detonation. The use of the relatively cheap ammonium nitrate and aluminium make it a replacement for pure TNT. The detonation velocity of ammonal is approximately 4,400 metres per second. (really big) Amatol A highly explosive material made from a mixture of TNT and ammonium nitrate. Amatol was used extensively during the First World War and the Second World War. Typically, Amatol was used as an explosive in military weapons such as aircraft bombs, shells, depth charges and naval mines. These were highly attractive features during major wars, when there was an insatiable demand for high explosives.

Interesting Facts Fritz Haber is known as the father of chemical warfare. In addition to the invention of the Haber process it was Haber who first came up with the idea of using chlorine gas as a weapon. He first used chlorine gas in 1915 at the battle of Ypres, where it took the unsuspecting (and unprotected) French troops by surprise. The gas killed over 10,000 of them in in few minutes. Over the next few years he developed other more lethal and nasty gases, such as phosgene and finally mustard gas, all of which were used against Allied troops. Mustard gas molecule attacking skin.. (ClCH2CH2)2S

TH 3 ND

Bibliography http://www.chm.bris.ac.uk www.wikipedia.org www.chemistry.org/education/chemmatters.html Google.com (images)