Ammonia Flashcards
Define reversible reaction
A reversible reaction can go both forward and backward at the same time, depending on the conditions under which the reaction is occurring
How is nitrogen obtained for Haber Process
Fractional distillation of liquid air
How can hydrogen be obtained for Haber Process
By the cracking of alkane(C18) or when methane reacts with steam
What are the conditions for cracking of C18 alkane to make hydrogen
High pressure, high temperature, catalyst
What are the conditions for methane reacting with steam to produce hydrogen
30 atm, nickel oxide catalyst, 800 degrees Celsius
What happens in compressor
Mixture of nitrogen and hydrogen, in volume ratio 1:3 is sent to compressor where they are subjected to pressure of 200atm
What happens in converter
Pressurised gases are heated to temperature of 450 deg C and passed over finely divided iron catalyst
What percentage of H2 and N2 have been converted to ammonia in first stage
About 10-15%
Conditions for nitrogen reaction with hydrogen
200 atm, 450 deg C, finely divided iron catalyst
What happens in cooling chamber
Mixture of gases is cooled. Only ammonia gas condenses to form liquid ammonia and is thus removed from other two gases. Unreacted nitrogen and hydrogen are pumped back into converted for further reaction
Define dynamic equilibrium
Speed of forward reaction is equal to speed of backward reaction (amount of products and reactants remain unchanged)
State Le Chatelier’s Principle
If a system in equilibrium is subjected to a change which disturbs equilibrium, the system responds in a way to counteract the effect of the change
Why is high pressure favored in Haber Process
Pressure of equilibrium mixture is increased, reaction mixture will try to decrease the pressure. Can do so by decreasing number of moles of gas present, forward reaction is favored as it produces fewer molecules, causing fall in pressure
Why is 200 atm selected as compromise despite needing high pressure
Expensive equipment such as special pump and stronger pipes that can withstand high pressures would be needed
Why is lower temperature favored for Haber Process
When temperature of equilibrium mixture of gases is decreased, reaction mixture will try to increase the temperature and can do so by releasing heat. Hence forward reaction is favored as it releases heat
