Where do we get aluminium and iron from?
- ores
- minerals we get useful materials from
How is glass made?
- limestone, sand (silicon dioxide) and soda (sodium carbonate)
- heat until it melts
- when cooled it comes out glass
How are bricks made?
- from clay (soft when dug up, so easy to mould)
- it hardens by firing at very high temperatures
How is cement made?
- clay contains aluminium and silicates
- powdered clay and limestone roasted in rotating kiln making a complex mixture of calcium and aluminium silicates (cement)
What is reinforced concrete and why is it useful?
- is a composite material
- combination of concrete and solid steel support (like steel rods)
- better for construction than ordinary concrete
- as it combines the hardness of rock with steel’s flexibility and strength
What are composite materials?
-a mixture of materials
Why is extracting rocks from the environment dangerous?
- quarrying uses up land and destroys habitats (costs money to improve the look of quarry sites)
- transporting rocks causes noise and pollution
- quarrying process creates lots f dust and noise (dynamite to blast rocks out of ground)
- disused sites dangerous, turn into incredibly deep lakes
- disused mines can cause subsidence
How is pure copper obtained?
-through electrolysis
1-copper immersed in a liquid called the electrolyte which conducts electricity
-electrolyte are usually fee ions dissolved in water
2-copper (II) sulfate is the electrolyte used for purifying copper (contains Cu2+ ions)
3-pass a current through impure copper, the electrical supply acts like an electron pump:
*electrons pulled off copper atoms at the anode, causing them to go in solution as CU2+ ions
*offers electrons at the cathode to CU2+ ions to turn them back to copper atoms
*impurities dropped at the anode as sludge, while pure copper atoms bond to the cathode
What does electrolysis mean?
- splitting away with electricity
- in coppers case passing a current through impure copper splits the pure copper off from impurities
What is the cathode and its use in extracting copper?
- negative electrode
- starts as a thin piece of pure copper and more copper is added
- pure copper deposited at the pure cathode
What is the anode and its use in extracting copper?
- positive electrode
- big lump of impure copper which will dissolve
- copper dissolves from the impure anode
What is OILRIG?
- oil is loss of electrons
- reduction is gain of elections
How does recycling save money and resources?
-
How is concrete made and what are the benefits?
- mixing cement with sand, aggregate and water
- very quick and cheap way to construction buildings
What happens if you mix cement with water?
-slow reaction takes place and causes cement to gradually set hard
What is reduction?
-removal of oxygen
What is oxidation?
-addition of oxygen
What is subsidence?
- mines collapsing
- includes sink holes appearing buildings cracking and railway lines twisting
