reverible reactions, industrial processes and important chemicals Flashcards
what is meant by a reversible reaction
a reaction that can occur in 2 directions
the products can react to form the original reactants
A+B ⇌ C+D
for A+B ⇌ C+D which are the products for:
forward reaction
backwards reaction
C+D is forward
A+B is backward
how can the direction of a reversible reaction be changed
by changing the conditions:
Pressure
temperature
concentration of reactants or products
If the reaction is exothermic, will the backwards reaction be endothermic or exothermic
Exothermic, the same amount of energy is transferred
What is the reaction in the harbour process
symbol equation
Nitrogen + symbol hydrogen ⇌ ammonia
N2+3H2 ⇌ 2NH3
What can ammonia be used for
To produce nitrogen-based fertilisers
what can nitrogen and hydrogen gas be a obtained from
Nitrogen can be obtained from the air
hydrogen Gas can be obtained from natural gas or other sources
What are the conditions required for the harbour process
High temperature (450°C)
High pressure (200 atm)
Iron catalyst
What happens during the harbor process
- purified gases passed over the iron catalyst
- Some nitrogen and hydrogen reacts to form ammonia
- Some ammonia breaks down into nitrogen and hydrogen (because reaction is reversible)
- The mixture is called, ammonia liquefies and is removed
- The remaining nitrogen and hydrogen is recycled
What are the disadvantages of using a low temperature and a very high pressure
Low temperature causes slower rate of reaction
High pressure requires high energy
What are two things that want to be maximised when choosing the conditions of the have a process
The rate of reaction and the yield of ammonia
How can the presence of ammonia gas be tested
Moist red litmus paper will turn blue as ammonia is alkaline
What are the advantages of using fertilisers
Increasing crop yields and growth
increase profit for farmers
What are the disadvantages of using fertilisers
It changes the pH of soil
can cause baby blue syndrome
many stages in manufacture
eutrophication my fertilisers are washed into rivers and lakes
Increase of nitrate and phosphate importer encourage algae growth
Algae bloom blocks sunlight from water plants underneath
Water plants die and are broken down by bacteria
Oxygen is used up by bacteria, killing other living organisms in the water
what is the contact process
the manufacture of sulfuric acid
what is the first stage of the contact process
sulfur is burned in air and reacts with oxygen to form sulfur dioxide
S + O2 —> SO2
(L) (g) (g)
what is the second step of the contact process
Sulphur dioxide is then oxidised (with the help of a catalyst) to make sulphur trioxide
SO2 + O2 ⇌ SO3
what is the final stage of the contact process
Oleum is then made by dissolving sulphur trioxide and concentrated sulphuric acid. The oleum is then converted to sulphuric acid by adding water
which stage in the contact process is reversible
the second stage
What are the uses of sulphuric acid
Most are used to make fertiliser
Manufacturers of chemicals (examples: HCl, dyes, plastics, detergent and paints)|
Processing metals
What does dehydrating agent do
Removes water from other compounds
How does concentrated sulphuric acid aact as a dehydrating agent with sugar
Concentrated sulphuric acid remove six water molecules per glucose (C6 H12 O6) molecule
Highly exothermic reaction
What are molecules released as steam and a black mass of carbon forms
What change can be observed when concentrated sulphuric acid acts as a dehydrating agent on hydrated copper (II) sulphate
Blue crystals (heated copper sulphate) —> White powder (anhydrous copper sulfate)
