Haber Process

The Haber process

• a position paper by Claudelle Tetteh

What is the Haber process?

We live in a world where are resources are constantly running out, why? cause as humans we seldom know how to preserve what was given to us freely by nature. The thin string,barely holding us in place and keeping us from breaking  into chaos, starvation and calamity, is the work of intelligent scientists who always miraculously to change anything deemed impossible into possible. This takes me back to the twentieth century, when a brilliant man, Fritz Haber developed a process involving the combination of the elements, nitrogen and hydrogen, in the ratio 1 : 3 to synthesis ammonia. This process was and is referred to The Haber process.

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  Nitrogen is found unreacted in the atmosphere, whereas hydrogen can be obtained from natural gas, petroleum,cracking ethane or by reacting steam with methane. The reaction is an equilibrium reaction, this means that the rate of reaction and the concentration of both the products and reactants are equal and an exothermic reaction . There are several factors which can affect an equilibrium, in this case the production of ammonia, some of the factors entail temperature, pressure and concentrations. A change of one of these factors can cause a shift in the reaction. For example, in an instance where the temperature is too high, there will be a decrease in the yield of ammonia. This is because high temperatures favor endothermic reactions( a reaction which absorbs heat from its surroundings) which in this case, is the reverse reaction. The reaction should occur at low temperatures, however when the temperature is too low there would still be a decrease in the yield of ammonia because the rate of reaction will be too slow. In order to produce a sufficient amount of ammonia, a compromise temperature of 450 degrees Celsius is used.In the instance in which pressure is increased,the reaction that produces the least number of [pic 2]molecules of gas is favoured. This means that the equilibrium yield of ammonia is increased if the pressure is increased.(BBC- GCSE bitesize science- making ammonia: revision, page 3). Unfortunately, achieving high pressures requires lots of energy, which is very expensive.According to Le Chatelier's Principle, if you increase the pressure the system will respond by favouring the reaction which produces fewer molecules. That will cause the pressure to fall again.

In order to get as much ammonia as possible in the equilibrium mixture, you need as high a pressure as possible. 200 atmospheres is a high pressure, but not amazingly high.( chemguide.co.uk) Even with these conditions the reaction still won’t be fast enough, so a catalyst, iron, is used. The catalyst does not affect the equilibrium it only facilitates the reaction.