Fritz Haber was a German
chemist. He won the
Nobel prize in 1918 for
“contributions to
agriculture” but there was N2(g) + 3H2(g)
some controversy due to
his contributions to
chemical warfare during
WW1
nitrogen + hydrogen
Nitric acid, fertilisers,
explosives, dyes,
household cleaners and
nylon all contain
ammonia.
Hydrogen is obtained by
reacting natural gas
(methane – CH4) with
steam, or through the
cracking of oil.
When hydrogen is burned
in air, the oxygen
combines with the
hydrogen, leaving
nitrogen behind.
2NH3(g)
ammonia
There are 3 conditions
which are needed for
ammonia production in
the Haber process
The pressure
Equilibrium is when a
compromise: The cost
The temperature
reversible reaction
of keeping a higher
o
compromise: 400-450 C reaches a point where the pressure than 200atm
produces a reasonably
rate of the forward
is more than the
high yield of ammonia in reaction is the same as the money gained from
a short time.
rate of the backwards
selling the ammonia.
reaction.
An increase in
An increase in pressure
temperature increases the Pressure is measured
shifts the equilibrium to rate of reaction (ammonia in “atmospheres”
the right (more
produced quickly). But it
(atm).
ammonia produced).
also shifts the equilibrium 10atm is 10x more
to the left.
than the normal
pressure.
A catalyst of iron is
used. It doesn’t increase
the yield of ammonia
produced, only the rate
of reaction.
In the Haber Process a
compromise has to be
made between pressure
and temperature to gain
the greatest, most
economical yield.
Which is better – more
ammonia (high yield)
produced very slowly,
or a small amount (low
yield) produced
quickly?
Ammonia is collected as
a gas. At this point the
temperature is lowered
and it turns into a liquid.
When the gaseous
ammonia is turned into a
liquid, the unused
hydrogen and nitrogen
stay as a gas and are
recycled.
Taking the liquid
ammonia away stops
the reaction going
backwards.
Who invented the Haber process?
What does it produce?
Why do we need it?
How does it work?
When does it produce the highest, most economical yield?