Chemistry · Factors affecting equilibrium: concentration, pressure, temperature, the effect of catalyst, Le Chatelier's principle

In the Haber process for the industrial manufacturing of ammonia involving the r

In the Haber process for the industrial manufacturing of ammonia involving the reaction \( N_{2}(g)+3 H_{2}(g) \rightleftharpoons 2 N H_{3}(g) \) at 200atm pressure in the presence of a catalyst, a temperature of about \( 500^{\circ} \mathrm{C} \) is used. This is considered as optimum temperature for the process because:

  • A. yield is maximum at this temperature
  • B. catalyst is active only at this temperature
  • C. energy needed for the reaction is easily obtained at this temperature
  • D. rate of the catalytic reaction is fast enough while the yield is also appreciable for this exothermic reaction at this temperature

Step-by-step solution

The Haber process is exothermic, so lower temperatures favor higher yield (Le Chatelier's principle). However, at low temperatures the reaction rate is impractically slow. A temperature of 500°C provides a compromise: the rate is sufficiently fast due to increased kinetic energy and catalyst activity, while the yield remains appreciable (though not maximal) for the equilibrium. Thus, option D correctly describes the trade-off between rate and yield.
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