Most of the topic Flashcards
What is sacrificial protection?
When a coating of another more reactive metal is applied, so the coating reacts with the oxygen instead of the actual metal
What is bronze an alloy of?
Copper and tin
What is brass an alloy of?
copper and zinc
What is soda-lime glass made of?
Sand, sodium carbonate, limestone
What is borosilicate glass made of?
sand, boron trioxide
What is the difference between borosilicate glass and soda lime glass?
Borosilicate melts at higher temperatures
How is clay made?
Wet clay is shaped and heated in a furnace
What is the structure of glass?
Irregular giant lattice
What are composites made from?
Two materials, a matrix or binder surrounding the reinforcement (the actual material)
Difference between the physical characteristics and structure of LD and HD polymer?
LD - Softer (less compact)
HD - Harder (more compact)
Conditions for making LD polymer?
Low temperature
Low pressure
Different catalyst
Conditions for making HD polymer?
Moderate temperature
Higher pressure
Catalyst
Describe the structure of thermosetting and thermosoftening polymer?
Thermosetting
Strong covalent bonds between polymer molecules, very strong
Thermosoftening
Weak intermolecular forces between the chains and heating breaks the forces
What is the haber process used for?
Producing ammonia which can be used in NPK fertiliser
What are the raw materials for the haber process and where do they come from?
Nitrogen (from air) and hydrogen (from natural gas)
Explain the haber process?
Nitrogen and hydrogen are passed over a iron catalyst at a high temperature of 450°C and a high pressure of 200 atm. Some of the hydrogen and nitrogen reacts to form ammonia. The reaction is reversible so some of the ammonia produced breaks down into nitrogen and hydrogen. The ammonia enters a cooling chamber, the ammonia liquefies and is removed. The remaining hydrogen and nitrogen are recycled.
Why is the ammonia removed from the haber process?
To provoke the reaction (le chateliers principle)
What is ammonia used to manufacture?
Ammonium salts and nitric acid
What is NPK fertiliser?
A formulation of ions of nitrogen, phosphorus and potassium
Compare the production of fertiliser in industry vs a lab?
Lab - dilute ammonia and nitric acid
Industry - Concentrated nitric acid, ammonia gas (exothermic reaction)
Lab - water bath with bunsen burner
Industry - Heated using the exothermic reaction (earlier)
Lab - Batch process
Industry - Continuous process
Is the haber process endothermic or exothermic?
Exothermic
Why is 200 atm used in the haber process? Why not higher?
Le chatelier’s principle. If you increase the pressure then the equilibrium will shift towards the side with the least number of gas molecules. In the haber process, the forward reaction has the least number of gas molecules so the pressure is increase so that more product is formed. The pressure isn’t above 200 atm because then it would be dangerous and expensive
Why is 450 degrees used, why not higher?
Le chatelier’s principle says if you increase the temperature then the products will decrease for an exothermic reaction so there would be less ammonia, so the temperature should be as low as possible, however if the temperature was too low then the rate of reaction and collisions would also be low, so 450 degrees is a used as a compromise between yield and rate
