THE HABER PROCESS

Question 1

what is the Haber process?

Answer 1

the industrial production of ammonia from hydrogen and nitrogen

Question 2

what temp. and pressure is it always done at? + what catalyst is used

Answer 2

450^C and 200 atm alongside an iron catalyst so reaction favoured with lower temp. & higher pressures

Question 3

use of the ammonia

Answer 3

• to make nitrogen based fertilizers

Question 4

how to obtain the hydrogen and nitrogen for Haber process

Answer 4

78% nitrogen in air so taken from air
hydrogen has to be made from hydrocarbons like methane

Question 5

properties of the reaction

Answer 5

• exothermic as it produces heat
• reaction is reversible so some ammonia formed will break back down forming reactants

Question 6

how Haber process works

Answer 6

1. hydrogen and nitrogen mixed in ration 1:3 in the reaction vessel at 450^C and 200atm with iron catalyst
2. 15% react to form ammonia but since its reversible mixture will maintain nitrogen + hydrogen
3. since NH3 has a low boiling point mixture is taken into condenser where gaseous ammonia turns liquid and H2+N remains gas
4. H2 + N2 recycled back round at repeated

Question 8

why these conditions for temp.? (% yield, rate of reaction & cost)

Answer 8

• conversion of N2 and H2 in exothermic process
• decreasing temp. will increase yield of NH3 but slows down reaction
• 450^C compromising temp. in which yield relatively good with fast enough reaction
• high temp. would be costly so 450^C good enough

Question 9

why these conditions for pressure? (% yield, rate of reaction & cost)

Answer 9

• forward reaction is accompanied by decrease in vol.
• so increase in pressure will shift equili. to side with less gas molecules (increasing ammonia yield)
• increase pressure increases reaction rate because collision frequency increases also
• high pressure is costly and dangerous as thicker pipes and tanks must be built