C15-using our resources Flashcards
what is rust
rusting = the corrosion of iron
what is needed for iron to rust
air and water are needed for iron to rust
what is the word equation for rust
iron + oxygen –> hydrated iron (III) oxide
what can you prevent rust with
You can prevent rust with:
paint
oil/grease
plastic
a less reactive material
a more reactive material –> iron is galvanised (coated with zinc) for sacrificial protection
what are alloys
alloys are mixtures of metals
what makes alloys stronger than pure metals
alloys are much stronger than pure metals due to their irregular structure that prevents the layers from sliding over each other
what is brass made off and what are its uses
brass = copper and zinc
uses: taps, door fittings, musical instruments
what is steel made off
Steel are alloys of iron+carbon and/or other elements
what makes a stainless steel
Chromium-Nickel steels are stainless steels
what do the properties of polymers depend on
the properties of a polymer depends on:
the monomers used to make it
conditions chosen to carry out the reaction
using very high pressures and a trace of O2 what polymer is formed
using very high pressures and a trace of O2, ethene forms LD Polyetheme (low-density)
the chains are randomly branched and cannot pack closely together
using a catalyst at 50degrees celsius and a slightly raised pressure what polymer is formed
using a catalyst at 50degrees celsius and a slightly raised pressure, ethene makes HD polyethene (high density)
has straighter chains that pack more closely - it has stronger and has a higher softening temperature than LD polyethene
what are thermosoftening polymers
thermosoftening polymers = soften quite easily and will re-set when they cool down. made of individual polymers that are tangled together. these can be remoulded
what are thermosetting polymers
thermosetting polymers = do not melt when heated - have strong covalent bonds forming cross-links between the polymer chains
