C1 - a (part 2) Flashcards
What is electrolysis?
The breaking down of a substance using electricity
When do metals have to be electrlysised?
When they are more reactive than carbon which makes process much more expensive
How is copper purified?
With electrolysis - it is impure when extracted with reduction and won’t conduct electricity so use electrolysis to make it pure and so can be used in electrical wires
How does electrolyisis work?
- Requires a liquid to conduct electricity - called electrolyte
- Electrolytes are often metal salt solutions from ore or molten metal oxides
- Electrolyte has a free ions - which conduct electricity
- Electrons are taken away from positive anode and given away be negative cathode
- As atoms gain or lose electrons they become atoms or molecules and are relaesed
Process of electrolysis of copper
- electrons pulled from copper atoms at the anode causing them to go into the solution as Cu2+ ions
- Cu2+ ions near cathode gain electrons and turn back to copper atoms
- Impurites dropped off at anode into sludge while pure copper atoms bond at cathode
What is displacement
putting a reactive metal into a solution of a dissolved metal compound. The reactive metal will replace the less reactive metal in the compound - this is because the more reactive metal bonds more strongly to the non metal part of the compound and pushes out less reactive metal
How do you extract copper using electrolysis?
Put iron into solution of copper sulphate
The more reactive metal will push out less reactive metal so…
copper sulfate + iron = iron sulphate + copper
What is bioleaching
Using bacteria to separate copper from copper sulfide. Bacteria gets energy from the bonds between copper and sulphur, separating out the coper from the ore in the process. The leachate (solution produced by process) contains copper which is extracted by filtering
What is photomining
Growing plants in soil that is rich with copper. Plant can’t use or get rid of copper so it gradually builds up in the leaves. The plant then harvested, dried and burned in a furnace. copper is collected from ash
How is metal extraction bad for environment
Noise/air polluion
loss of habitat
destroy landscape
mine shaft dangerous
Why is recycling important?
Saves energy and fossil fuels Reduce co2 that causes global warming\ Uses less energy save money - energy expensive finite amount of metal on earth cuts down landfills
Properties of metals
strong
can be bent or hammered
conduct heat
conduct electricity
Why are metals used - e.g
Bridges/ car bodies - bendability and strength
Saucepan base - heat travel through
electric wires - electricty moves through
Properties of copper
Good conductor of electricity so good for electrical wires
hard, strong but can be bent
dotn react with water
Properties of aluminium
Corrosion resistant low density not particularly strong form hard alloys aeroplanes
Properties of titanium
Low density
very strong
corrosion resistant
replacement hips
Disadvantages of metal
Some corrode when exposed to air/water
Need to be protected
Look tired over time - stains/ break which is dangerous
Whats an alloy
Mix of 2 or more metals
Whats wrong with pure iron
TOO BENDY
perfect layers slide over each other - so VERY easily shaped and too bendy
Different types of steel
Low carbon steel - easily shapped - car bodies
High carbon steel - hard,inflexible - bridges
Stainless steel - corrosion-resistant - cutlery
Different types of alloys
Bronze = copper + tin Gold = pure gold and zinc/silver (jewellery) Cupronickle = copper + nickel
What is crude oil?
a mixture of many different compounds - mainly hyrdocarbons (not chemically bonded)
Why can crude oil be separated?
Theres no chemical bonds so all the different element have original properties. So this means that the mixture can go through fractional distillation and separate when they condense at different stages
Process of splitting crude oil
Heat crude oil at base
Vaporised oil rises up column and various fractions trapped off at different levels when they condense - seperate
