c10 Flashcards
why are thermosoftening polymers easier to recycle than thermosetting polymers? (2)
- it melts when heated
- can be reshaped into different products
how can different forms of poly(ethene) be produced from ethene? (1)
use different reaction conditions (different temperatures or pressure)
what salt is produced when calcium phosphate is reacted with nitric acid?(1)
calcium nitrate
what salt is produced when calcium phosphate is reacted with phosphoric acid?(1)
triple superphosphate
what is the issue with lead?
lead is toxic
how is copper extracted from low-grade ores by phytomining? (4)
- grow plants (in soil containing copper compounds and plants absorb them through roots)
- plants are burned
- ash , containing copper compound, is dissolved in acid to produce solution of copper compound
- copper extracted by electrolysis of solution or displacement by iron
why is phytomining not use widely? (3 reasons)
- high grade ores are still available
- land not available
- new technology
why is it useful to farmers to know the proportion of nitrogen, phosphorus and potassium in NPK fertilisers? (2)
- shows that fertilisers are formulations
- so farmer can choose fertilisers with required properties
when producing ammonia in the haber process, what happens to unreacted hydrogen and nitrogen? (1)
recycled to reactor
name a source of methane
natural gas
why can’t air get into the reactor during the haber process? (2)
- air contains oxygen
- this would react with hydrogen
during the haber process, what happens to the mixture of gases from the reactor? (3)
- cooled
- ammonia condenses to be separated
- nitrogen and hydrogen are recycled back to the reactor
what are two disadvantages of the use of poly(propene)?
- comes from a non renewable source
- not biodegradable
what is a disadvantage of the use of wool?
wool required large areas of land which could be used for other things
describe how ceramic plates are produced from clay (2)
wet clay is shaped and heated in a furnace
why doesn’t melamine melt when heated?
it is thermosetting
it has cross-links between polymer chains
what is a property of stainless steel?
resistant to corrosion
why does coating a steel ship in magnesium prevent steel from rusting? (2)
magnesium is more reactive so will react with oxygen and hydrogen first as sacrificial protection
why don’t aluminium window frames corrode after they are made? (2)
aluminium has a coating of aluminium oxide
which protects the metal from further corrosion
what are composites made from?
one material embedded in another
what types of metals are usually used as catalysts?
transition metals
what are ways to prevent rusting
- painting
- electroplating
- oiling/ greasing
- galvanising
what is the reinforcement of a composite?
the fibre of fragment inside the matrix
what is the matrix of a composite?
surrounds the reinforcement
