Manufacture of Ammonia - Haber's process Flashcards
Reactants
Nitrogen
Hydrogen
1:3 ratio by volume
Product :
Ammonia - 2 volumes
NH3
Conditions
Reaction :
Reversible
Exothermic
Proceeds with a - decrease in volume
Low temperature and high pressure - favour the forward reaction
Temperature
Pressure
450- 500*
200-900 atmospheres
Catalyst :
Finely divided Iron [Fe]
Promoter :
Molybdenum
Precaution :
Impurities like CO , CO2 , H2S may poison the catalyst
Hence the nitrogen - hydrogen reactant mixture must be free from them
Reactant Nitrogen gas is obtained by
Fractional distillation of liquid air
Reactant hydrogen obtained from
Water [ Bosch process ]
Higher ratio of hydrogen -
or an increase in concentration of the reactant favors the forward reaction to give optimum yield of ammonia
Reactant should be free from impurities
Pure and dry since impurities tend to poison the catalyst and reduce effectiveness
Temperature
above this optimum temperature what will happen
Ammonia may decompose to give nitrogen and hydrogen
Why external heat is not required?
after the reactant are initially
since its exothermic the evolved is further maintains the temperature
if a reaction proceeds with decrease in volume
then the forward reaction is favoured by increasing pressure
What happens if the pressure is too high ?
the production plant can’t withstand the pressure
Why catalyst is required?
to accelerate the reaction
Catalyst job
only accelerates the reaction
does not form a part of reaction
does not affect the percentage of yield of ammonia
ammonia is seperated from uncombined Nitrogen and Hydrogen
Liquefaction :
Ammonia is easily ______
it condenses to a liquid at ________
_______ and __________ are difficult to liquefy
they are condense at temp at ___________ and _________
Liquefiable
-33*C at 8 atmos press
N2 , H2
-196 C , -253C
