Fundamental Research on the Thermodynamics of Direct Ammonia Synthesis from Its Elements

FUNDAMENTAL RESEARCH ON THE THERMODYNAMICS OF DIRECT AMMONIA SYNTHESIS FROM ITS ELEMENTS 

By the time Haber had initiated his measurements on the nitrogen/hydrogen/ammonia equilibrium point, many attempts had been made to study the synthesis and decomposition of ammonia. Some of them had been successful to 

It was already generally accepted that molecular nitrogen was too inert to react directly with hydrogen at moderate temperatures. Unfortunately, at high temperatures where reaction with hydrogen becomes possible, the decomposition of ammonia also takes place, hence the need for a catalyst to allow synthesis at the reaction temperature. Perman used iron as a catalyst in 1904 and studied the formation of ammonia from its elements, but, unfortunately for him, in the presence of moisture which we now know retards the reaction. Haber immediately realized that the equilibrium concentration of ammonia should not be infiuenced by the presence of moisture. 

Haber started his work on measurement of the equilibrium point using iron as a catalyst at temperatures around 1300 K, and at atmospheric pressure. He knew, of course, that higher pressures would give higher concentrations of ammonia, but the measurements at atmospheric pressure could be carried out much more simply and easily. He placed two reaction tubes in series and measured 

The values obtained by Haber and van Oordt for the concentration of ammonia at equilibrium from a stoichiometric mixture of hydrogen and nitrogen, at 1020 X under atmospheric pressure, are as follows  

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