In reversible reactions, the products can react to produce the original reactants again
What does ammonium chloride look like?
Whitesolid
What is hydrogen chloride?
A colourless gas
What does anhydrous mean?
A substance which doesn't contain any water
What is the symbol for ammonia?
NH3
Why is ammonia important?
For the manufacture of fertilisers, can be found in cleaning products and is a raw material
Some ammonia is converted into nitric acid which can be also used for the manufacture of fertilisers and explosives
How is nitrogen made available for plants?
Ammonia enables them to build protein molecules
Why can't plants use nitrogen directly from the air?
They need nitrogen compounds to be able to absorb them in their roots as it can dissolve in water
Ammonia is an alkaline gas
What colour does ammonia turn damp litmus paper?
Blue
How can ammonium compounds be identified?
Heating the solution with sodium hydroxide
What is the ionic equation for a reaction between ammonium ions and sodium hydroxide?
NH4 (+) + OH (-) -> NH3 + H2O
What are the raw materials required in the Haber process for making ammonia?
Hydrogen and nitrogen
How can hydrogen be obtained?
Reacting natural gas (mostly methane) with steam or from cracking in oil fractions
Where is nitrogen obtained from?
The air
What are the 3 conditions needed for the production of ammonia?
High temperature = 350-450 degrees+
High pressure = 150-200 atm+
Catalyst = iron
What happens to leftover hydrogen and nitrogen in the Haber process?
They are recycled because the equation is reversible
What is the ionic equation for the Haber process?
N2 + 3H2 -> 2NH3
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How is ammonia obtained in the Haber process?
Hydrogen and nitrogen are pumped into the compressor through pipes after being obtained
Gases are pressurised to 150-200 atm inside the compressor
Pressurised gases are pumped into a tank containing iron catalyst at 350-450 degrees where some hydrogen and nitrogen will react to form ammonia
Unreacted hydrogen, nitrogen and ammonia pass into a cooling tank which liquefies the ammonia. It is then removed into pressurised stroagevessels (expensive)
Unreactedhydrogen and nitrogen gases are recycled
What happens to the ammonia in the cooling tank?
Cooled and compressed, causing it to condense into a liquid where it is then separated and removed
The Haber process is a reversible reaction
How can the yield of ammonia be changed?
By changing the pressure and or temperature of the reaction
What happens if you increase the pressure of the reaction?
Increases yield of ammonia, but if the pressure becomes too high, it becomes too expensive to be stored by the storagevessels
What happens if you increase the temperature of the reaction in the Haber process?
Decreases yield of ammonia
What happens if the temperature in the Haber process is too low?
Increases yield of ammonia, but slows the rate of reaction
Why is a pressure of 200 atm chosen in the Haber process?
Decent yield, increases rate of reaction
What would happen if the pressure in the Haber process was higher than 200 atm?
Higher risk of an explosion
Why is a temperature of 450 degrees chosen in the Haber process?
Decent yield, maintains rate of reaction, little reactants are wasted
Why are compromised conditions used in the Haber process?
To ensure that there is a decent yield of ammonia, while simultaneously being costeffective and not too expensive
Why is an iron catalyst used in the Haber process?
To speed up the reaction
What happens when the iron catalyst stops working?
The catalyst is deemed as poisoned, so therefore needs to be replaced regularly
The most effective fertilisers contain what element?
Nitrogen - helps plants to produce proteins
What are the advantages of using fertilisers?
Increases crop growth and yield and increases quality of soil
What are the disadvantages of using fertilisers?
Eutrophication, baby blue syndrome, turns soil acidic
Most fertilisers are ammonium salts
What happens in the contact process?
Used for creating sulfuric acid
What raw materials are needed for the contact process?
Sulfur, air and water
What happens in the first stage of the contact process?
Sulfur is burned in the air to make sulfurdioxide. It is not a reversible reaction.
Sulfur + Oxygen -> Sulfurdioxide
Why shouldn't sulfur dioxide be released into the atmosphere?