haber process

what is the Haber process?

-manufactures ammonia from nitrogen and hydrogen

reaction equation

N2 (g) + 3H2

energy change of the forward reaction

-93kJ/mol -exothermic

usual conditions chosen

-pressure of 200 atmospheres/ 20 MPa -a temperature of 450 degrees Celsius -an iron catalyst

yield of ammonia in chosen conditions

-about 30%

why is the pressure chosen?

-increased pressure moves to right -however, cannot increase the pressure too much as it would be hazardous and expensive -increased yield would not justify the additional costs

why is the temperature chosen?

-the forward reaction is exothermic -if the temperature is increased, the equilibrium moves to the left, so low temperatures produced a higher yield -the temperature is a compromise: low enough to achieve reasonable yield, but high enough to achieve a reasonable rate of reaction -also, the iron catalyst works best above 400 degrees Celsius

what other conditions are chosen?

-the mixture of gases leaving the reaction is cooled so that ammonia is a liquid -this allows the ammonia to be removed, and unreacted nitrogen and hydrogen to be recycled -this improves the overall yield to about 97%