The Production of Ammonia Flashcards
What are the raw materials needed for the Haber process and where are they obtained from?
nitrogen - air
hydrogen - natural gas or water
How is ammonia produced using the Haber process?
The purified gases are passed over a catalyst of iron at a high temperature (about 450 °C) and a high pressure (about 200 atmospheres)
Some of the hydrogen and nitrogen reacts to form ammonia
The reaction is reversible so ammonia breaks down again into nitrogen and hydrogen
On cooling, the ammonia liquefies and is removed. The remaining hydrogen and nitrogen are recycled
How is an equilibrium obtained?
When a reversible reaction occurs in a closed system, equilibrium is reached when the reactions occur at exactly the same rate in each direction
What happens to the yield of a substance in an equilibrium if the temperature changes?
If the temperature is raised:
the yield from the endothermic reaction increases
the yield from the exothermic reaction decreases
vice versa
What happens if pressure changes in a gaseous reaction?
an increase in pressure will favour the reaction that produces the least number of molecules
as shown by the symbol equation for the reaction
Why is a temperature of 450 degrees C used in the Haber process?
the forward reaction is exothermic, so more ammonia is made in cooler temperatures
however, a lower temperatures means the particles collide less frequently, causing a low rate of reaction
therefore, a compromise has to be made of 450
Why is a pressure of 200atm used in the Haber process?
there are fewer molecules on the right side
if pressure is increased, the yield of ammonia will increase
high pressure requires strong equipment and lots of energy
