Using resources pt2 : using materials Flashcards
What materials make metals, glass, building materials, clay ceramics and most plastics?
limited raw materials
crude oil
What is the main downside of mining and quarrying?
devastating environmental impact
Why are materials reused or/and recycled whenever possible?
to :
- save money and energy sources
- reduce the use of limited resources
- reduce the number of waste products
- reduce damage to the environment caused by extinction
How can metals be recycled?
by melting and recasting or reforming into different products
How can glass be recycled?
crushed and melted to make different glass products
What can some plastics be recycled into?
fleece materials
Why is recycling good for the environment?
- uses less energy than the initial extraction and production processes
- less fossil fuel is burned and fewer greenhouse gases are released into the atmosphere
- preserves our reserves of raw materials of the future
What is corrosion?
the destruction of materials by chemical reactions with substances in the environment
What is the word equation for the rusting of iron?
iron + water + oxygen = hydrated iron ( III) oxide
Corrosion only happens ….
on the surface of a material, where it’s exposed to the air
how can corrosion be prevented?
by painting, electroplating or greasing a metal object to stop oxygen and water from reaching the surface and therefore stop corrosion from happening
What happens when coating on a metal is damaged?
the metal start to corrode
What is sacrificial protection?
when a more reactive metal is placed in contact with the metal
the more reactive metal reacts and loses its electrons instead of the iron or steel object its protecting
What is electroplating?
using electrolysis to reduce metal ions onto an iron electrode. Can be used to coat with the iron with a layer of a different metal that won’t be corroded away
How can rusting with metals be prevented in a decorative way?
painting/ coating with plastic
How can rusting be prevented with moving parts?
oiling and greasing
What is galvanising?
applying a layer of zinc to protect iron or steel objects
How does galvanising work ?
- the zinc layer stops oxygen and water from reaching the metal and stops corrosion
- the surface of the zinc is scratched, it does not matter, the zin provide sacrificial protection
How are aluminium objects protected from corrosion?
by a thin layer of aluminium oxide which acts as a barrier and presents the aluminium from reacting further
How do rusting damage metals?
it makes the metal flake off to leave more metal underneath available to rust again.
this means that eventually, all the iron in an object corrodes away even if it wasn’t initially at the surface
Why doesn’t aluminium completely destroy under corrosion?
because the aluminium oxide formed doesnt flake away.
It forms a nice protective layer that sticks firmly to the aluminium below and stops any further reaction taking place
What is bronze an alloy of and what is its properties?
copper and zinc
extremely hard, tends not to corrode
What is brass an alloy of and what is its property?
only one main property
copper and zinc
malleable
What is gold usually an alloy with and what is it normally used as?
silver, copper and zinc
used jewellery
What does 24 karats and 18 karats gold mean?
24 = 100% 18 = 75%
What is steel an alloy of and what does it contain?
iron
it contains specific amounts of carbon and other metals
How is rusting prevented in steel?
chromium and nickel prevents this
Aluminium alloys are ____ density
low
