Haber process
-nitrogen gas 
1 mole of nitrogen gas and 3 moles of hydrogen gas react to produce ammonia gas with following conditions :
*with the presence of powdered iron as catalyst 
*pressure of 200-500 atmospheres 
*temperature between 450-550 degree celcius
ammonia gas formed is cooled down to liquid
unreacted nitrogen gas & hydrogen gas is pumped back to catalytic column to be reacted again