extraction and uses of metals Flashcards
what are minerals?
Minerals are a solid inorganic substance of natural occurrence
what is an ore?
a naturally occurring rock that contains enough of a metal or metal compound to make it economically feasible to extract the metal.
what does it mean to be found native?
this is when few unreactive metals can be found in their natural form when they are an uncombined element. e.g., gold, some silver and copper
what is roasting?
when a compound is converted into an oxide by heating in air
what is reduction?
to obtain the metal from the oxide, you have to remove the oxygen. this is called reduction.
this is because metals exist as positive ions in their ionic compounds, and to produce the metal you would have to add electrons to the positive ion.
this is aka the addition of electrons
what does the way a metal is extracted depend on?
- cost of energy
- cost of reducing agent ( a substance that donates electrons to another substance, causing it to be reduced)
what is a reducing agent?
a substance that donates electrons to another substance, causing it to be reduced
how do you extract metals which are below carbon in the reactivity series?
the cheapest method of reducing the ore is to head it with carbon.
this is because carbon is higher in the reactivity series than iron and will take the oxygen away from the metal oxide
what is the main reducing agent in extraction of metals below carbon in the reactivity series?
carbon monoxide or carbon
where is the extraction of iron carried out?
in a blast furnace
how are metals higher than zinc in the reactivity series extracted?
electrolysis
this requires a huge amount of electricity, making it expensive.
metals below carbon can be extracted by electrolysis but it doesn’t make economic sense to do this
why aren’t metals higher than zinc in the reactivity series extracted using carbon?
- they are more reactive than carbon and therefore carbon cannot take away the from the metal oxide.
what is another way metals can be extracted. use titanium ot explain.
you can extract it by heating the compound with a more reactive metal which is also an expensive method as the more reactive metal will have to be extracted by an expensive process first
what is an alloy?
a mixture of a metal with, usually, other metals or carbon
what is brass a mixture of
copper, zinc
are alloys harder or softer than pure metals. why?
alloys are harder than the individual pure metal from which they are made.
- In an alloy, the different sized atoms and this breaks up the regular lattice arrangement and makes it more difficult for the layers of ions to slide over each other
what is bronze made of?
copper, tin
what is aluminium usually mixed with? what are the uses of aluminium?
- common aluminium alloys are usually mixed with other elements like silicon, copper, or magnesium
- uses of aluminium:
planes, electricity cables, pots and pans
what can the uses of alloys depend on?
its low density, and strength, ability to conduct electricity and heat, ability to resist corrosion
does aluminium resist corrosion? why/why not?
yes
- it has a very thin but strong layer of aluminium oxide on the surface which prevents anythign else reaching the surface and reactign with it
what is corrosion?
the gradual destruction of a metal by chemical reactions with its environment, such as oxygen and water
name some different alloys of steel.
mild steel, high-carbon steel, stainless steel
describe some properties and uses of mild steel. are there any dissadvantages?
- contains around 0.25% carbon
- this increases the hardness and strength of iron
- therefore it is a strong material that is malleable and ductile
- it can be used in nails, car bodies, ship building , girders, and bridges
DISSADVANTAGES: - it rusts when exposed to oxygen and water. it is also about 3x denser than aluminium
- therefore many cars are made out of aluminium because it doesn’t rust and it is lighter, so less fuel will have ot be used
describe some properties and uses of high-carbon steel. are there any dissadvantages?
- contains about 0.6-1.2% carbon
- makes it harder and more resistant than mild steel
- however also more brittle than mild steel (not as malleable or ductile)
- it is used for cutting tools
- it can also be used for masonry nails
- sometimes it contains small amounts of manganese
describe some properties and uses of stainless steel. are there any dissadvantages?
it is an alloy of iron, chromium and often nickel
- chromoium forms a strong layer in the same way as aluminiums which protects the iron.
- therefore stainless steel is very reisstant to corrosion
- it can be used in cutlery, cooking utensils, kitchen sinks
- you can also use it in brewing (beer making) and dairy (cheese and milk production) - where corrosion resistant vessels are esssential
- it is significantly more expensive than mild steel
what are some uses of copper?
- electrical wires
- pots and pans
- water pipes
- surfaces in hospital
what are some properties of copper? how to these relate to its uses?
- very good conductor or electricity and ductile.
- vg conductor of heat (thermal conductor),
- very unreacitve
- malleable
- antimicrobial properties
what are most metals found as in earth’s crust?
ores
what are unreactive metals often found as when being extracted?
they are often uncombined
what are some uses of iron?
- used in construction because it is malleable and ductile + relatively inexpensive
- catalyst (Variable oxidation state* Increases the rate of reaction without being used up)
- Cast iron is made from molten iron that contains carbon impurities. It is brittle and is used in wood-burning stoves, man-hole covers, and engines.
what are some uses of steel?
- construction, transportation, and manufacturing like cutlery and car body panels
