C15.6 The economics of the Haber process Flashcards
How is hydrogen made for the Haber process?
Methane + Steam makes hydrogen + carbon monoxide
How is nitrogen made from methane gas?
The flammable gases are mixed with air and react with oxygen in a reaction vessel - this removes the oxygen from the air - mainly leaving nitrogen gas
What is the balanced symbol equation of the Haber process?
N(2) +3H(2) reversible reaction NH(3)
What will an increase in pressure to in the Haber process?
There are more moles of reactants than products - will tend to shift the equilibrium to the right - producing more ammonia to reduce the pressure
How can you get the maximum possible yield of ammonia?
You need to make the pressure as high as possible
What are the problems with high pressures?
High pressures need lots of energy to compress the gases - also need expensive reaction vessels and pipes.
They have to be strong enough to withstand high pressures otherwise there is a danger of exploisions
Why does the Haber process use a pressure of 200 atmospheres?
This pressure gives a lower yield than it would be with even higher pressures - reduces cost and helps produce a reasonable rate of reaction between the gases
What would lowering the temperature do?
Increase the amount of ammonia in the reaction mixture at equilibrium
Happens because the forward reaction to form ammonia transfer energy to the surroundings - thereby raising the temperature of the surroundings ( opposing the change introduced)
What are the problems of having a low temperature?
Rate of reaction would be very slow
Running a chemical plant is expensive - ammonia is needed to be made quickly
Low temperature would also reduce the effectiveness of the iron catalyst
What are the compromises for the Haber process?
Getting a reasonable yield of ammonia
Getting the rate of reaction to take place at a fast enough rate
What does the iron catalysts do?
Speeds up the rate of both forward and reverse reactions by the same amount - Therefore it does not affect the actual yield of ammonia - but it causes ammonia to be produced more quickly - an important economic consideration in industry
