Obtaining and using metals Flashcards
give two ways of extracting metals from their ores
heating with carbon, electrolysis
give an example of extracting a metal by heating it with carbon
metals such as iron are extracted from their compounds by heating the ores with carbon.
give a word equation of heating iron with carbon
iron oxide + carbon > iron + carbon dioxide
give an example of extracting a metal by electrolysing it
reactive metals such as aluminium are extracted by melting the ore and then carrying out electrolysis. electrolysis decomposes aluminium oxide.
give a word equation of electrolysing aluminium oxide
aluminium oxide > aluminium + oxygen
Explain why the method used to extract a metal is related to its position in the reactivity series and cost of the extraction process
most reactive elements are the hardest and most expensive to extract and they are extracted through electrolysis of a molten compound. less reactive, the easiest and cheapest to extract.
what an oxidation reaction
a reaction where oxygen is gained
what an reduction reaction
a reaction where oxygen is lost
does the extraction of metals involve oxidation or reduction
it involves reduction
what does the oxidation of metals cause
it causes corrosion
what is the link between a metals resistance to corrosion and its position on the reactivity series.
the most reactive metals are the least resistant to corrosion and they corrode the fastest. metals lower in the reactivity series are more resistant to corrosion and corrode the slowest. the metals lowest in the reactivity series are most resistant to corrosion and do not corrode at all.
give 6 advantages of recycling metals
1) means that the earth’s supply of metals will last longer
2) if metals are recycled we need fewer mines. this helps the environment, because mining causes dust and noise pollution and damages the landscape.
3) produces less pollution
4) less land is needed for landfill sites
5) carbon dioxide is emitted when fossil fuels are used to heat ores or to generate electricity used in electrolysis. so far less carbon dioxide is emitted by the recycling process, as less energy is needed.
6) it takes less energy to melt down used metals than it does to extract the metal from its ore. this makes some recycled metals more sustainable and cheaper.
Describe the uses of gold in relation to its properties
used for jewellery because it looks attractive and it does not corrode. used in some electrical connections inside electronic devices because it is one of the best electrical conductors.
Describe the uses of copper in relation to its properties
used for electrical cables because it is a very good conductor of electricity. used in water pipes because it does not corrode easily
Describe the uses of steel in relation to its properties
used for bridges, cars and buildings because it is strong and resistant to corrosion.
Describe the uses of aluminium in relation to its properties
used for drinks cans because it does not corrode. used in aeroplanes and some cars because it has a low density
why converting pure metals into alloys
often increases the strength of the product
in a pure metal the layers of atoms can slide over each. an alloy is stronger, because the atoms of the added metal are different sizes and they jam up the structure and stop the layers from sliding.
give an example of a alloy
steel is an alloy of ion with small amounts of other metals and some carbon. steel is stronger than iron and more resistant to corrosion.
describe how gold is alloyed
pure gold is alloyed with other metals to make it stronger and harder.
describe smart or shape memory alloys, give an example
smart materials have different properties in different conditions. shape memory alloys are smart materials, as their shape changes when the temperature changes. nitinol is an alloy of nickel and titanium. if the shape of something made from nitinol is changed, it will return to its original shape when it is heated.
give a use of shape memory alloys
shape memory alloys are used to make spectacle frames. these alloys are examples of new materials developed to meet new needs.
give one use of nitinol
it is used to keep arteries open. a stent is made from a tube of nitinol, which is cooled and squashed, so it is small enough to slide into the blocked artery. when the nitinol warms up to body temperature it resumes its original shape and holds the artery open.
what does carats measure
the percentage of gold in a gold alloy
what does fineness mean
fineness is the parts per thousand of gold in the alloy
