Although both nitrogen and hydrogen are abundantly available,
ammonia itself is not readily found in nature because of the strengh of the N to N bond which must be broken before it
can combine with hydrogen to form NH3.
In ancient times, ammonia was derived from organic substances
like manure or urine. During the middle ages ammonia was even collected from distilling the horns and hooves of oxen.
This solution was called 'spirits of hartshorn'. In the 18th and 19th centuries ammonia was recovered from vapours of natural
steam vents and large quantities were produced from Chile salpeter which is sodium nitrate, NaNO3. At the
end of the 19th century, Chile Salpeter supplies were running out and it was realised that unless new source of nitrogen compounds
could be found, food production would suffer and there were fears of the world population starving. Many scientist
and chemists started working on ways to form ammonia from nitrogen and hydrogen. In 1909 a German chemist Fritz
Haber became the first person to successfully synthesize ammonia in a laboratory. Haber's process used
a catalyst in the synthesis reaction which took place at very high temperature and pressure.
In 1913 another German, Carl Bosch developed Haber's process
further so that it could be practically produced in large scale industrial plants. This process then became known as
the Harber-Bosch process.
The Haber process was one of the most important milestones in
the chemical industry and the process of combining nitrogen with hydrogen in the form of ammonia contributed to the rapid
growth of the chemical industry in the 20th century. In recognition of this, Fritz Haber was awarded the Nobel Prize
for chemistry in 1918 "for the synthesis of ammonia from its elements".
Click here for more information on Fritz Haber's Nobel Prize award and the presentation speech. Close the link (X button)
The reaction for ammonia synthesis is given by:
N2 + 3 H2 < == > 2 NH3
(14x2) + 3(1x2) => 2(14+ 3)
By using atomic weights for nitrogen (14), hydrogen (1) and
ammonia (17) we get the mass balance for this reaction:
28 units of mass of nitrogen + 6 units of mass of hydrogen
will give 34 units of mass of ammonia.