C1.3 Metals and their uses Flashcards
What does it mean if an ore is concentrated?
getting rid of the unwanted rocky material
Why is gold not found as a compound?
As it is very unreactive
What are the 2 ways a metal can be extracted from their ores chemically
electrolysis
reduction
When can metals be extracted by their oxides with reduction?
When the metal is less reactive than carbon.
What happens during reduction with carbon?
oxygen is removed from the compound
eg iron oxide is reduced in the furnace to make iron
How are metals that are more reactive than carbon extracted?
By electrolysis of molten compounds.
Why is electrolysis more expensive than reduction with carbon?
it uses a lot of energy.
Describe the extraction of copper from copper rich ores
Copper is first extracted from its ores in a furnace- reduction with carbon. The copper is then purified by electrolysis so it conducts electricity better- electrical wiring
What 2 ways can copper be extracted from low grade ores?
phytomining
bioleaching
Describe phytomining
a way of extracting copper from a low grade ore
uses plants to absorb metal compounds. Plants are then burned to produce ash that contains the metal compounds.
Describe bioleaching
A way to extract copper from low grade ores
uses bacteria to produce leachate solutions that contain metal compounds
What is a metal ore?
A rock which contains enough metal to make it economic to extract the metal.
Describe how copper can be obtained from solutions of copper salts
by electrolysis
Copper is attracted to the negative electrode as it is a positively charged ion. Here, it gains electrons.
Describe how ion can be used to obtain copper from copper sulfate
Scrap ion can be used to displace copper from solution as iron is more reactive than copper
copper sulfate + iron — iron sulfate + copper
Why can aluminium and titanium not be extracted from their oxides by reduction with carbon?
As they are more reactive than carbon
Why are methods to extract aluminium and titanium expensive?
- There are many stages in the process
- Large amounts of energy are needed.
Why is metal extraction bad for the environment?
- noise
- scarring of the landscape
- loss of habitats
- deep mine shafts can be dangerous if abandoned
What are some benefits of metal extraction?
- useful products can be made
- provides local people with jobs
- brings money into the area- so services such as transport and health are improved.
Why is recycling metals important?
- conserves resources- finite amount of each metal on Earth
- reduces landfill
- mining and extracting metals takes a lot of energy- so less fossil fuels are used if you recycle.
Iron straight from the blast furnace contains what percentage of iron?
96%
What do the impurities of iron straight from the blast furnace make it like?
brittle - so it has limited uses
What is iron straight from the blast furnace used for and why?
cast iron because of its strength in compression
What is steel a mixture of?
iron and carbon
what is a property of low-carbon steel?
easily shaped
what is a property of high-carbon steels?
hard
what is a property of stainless steel?
resistant to corrosion
Why are pure gold, copper, iron and aluminium mixed with small amounts of similar metals?
They are too soft for many uses and so are mixed with small amounts of similar metals to MAKE THEM HARDER for everyday use.
Why are alloys harder than pure metals?
Different elements have different sized atoms. This distorts the regular layers, making it difficult for them to slide over each other.
What are the elements in the central block of the periodic table know as ?
transition metals
Describe the properties of transition metals
- good conductors of heat and electricity
- bent or hammered into shape
What are some properties of copper that make it useful for electrical wiring and plumbing?
- good conductor of electricity and heat
- can be bent but is hard enough to be used to make pipes or tanks
- does not react with water
Why are aluminium and titanium useful metals?
low density
resistance to corrosion
What are some disadvantages of using metals as structural materials?
- Some corrode when exposed to air and water so need to be painted —– if a metal corrodes, it loses its strength and hardness
- Metal fatigue- leads to metals breaking- dangerous
Why is titanium more expensive than iron?
there are more stages in the process
more energy/materials are needed to extract it
titanium is more reactive than titanium so cannot be extracted using carbon
Why is air removed and replaced with argon in the reaction between titanium chloride and magnesium metal to produce titanium?
because oxygen in the air would react with magnesium and produce magnesium oxide
whereas argon is unreactive so does not react
Why is copper extracted from ores containing a low percentage of coper compounds?
copper ores are running out and are harder to find
copper metal is in demand
now economical to extract copper from low grade ores
Why is it difficult to dispose waste rock?
takes up a lot of space
What is used in phytomining to remove copper compounds from the land?
plants
what are some advantages and disadvantages of recycling materials from a ball point pen?
conserves resources
reduces use of landfill
less use of energy
less carbon dioxide produced
made from different materials
diffuculty and cost of separating the different materials
Why are alloys used in a ball point pen?
so it is hard and strong
so it is resistant to corrosion so it does not rust
Why does extracting copper from the land using traditional methods have a major environmental impact?
- produces large amounts of solid waste
- causes atmospheric pollution from carbon dioxide + sulphur dioxide
- more lorries to transport bulky material
Why is it economical to use scrap iron to get copper?
iron is cheap
Why can iron be used to get copper from copper sulfate solution?
iron displaces copper from solutions of its salts
because iron is more reactive than copper
What are some advantages of phytomining rather than using traditional methods to extract metal?
- carbon neutral - as plants remove carbon dioxide from the atmosphere as they grow
- less expensive as less energy is needed to extract the small amounts of copper
Suggest a disadvantage of phytomining rather than traditional methods to extract metals
it is not a continuous process as it takes a long time for plants to grow
What is smelting?
When copper is extracted from copper rich ores by heating the ores in a furnace
Suggest why an ore needs to be separated before the metal is extracted
as the ore is not pure
so the other compounds need to be removed
Describe how cast iron is converted into steel
in the furnace, oxygen reacts with the carbon in the iron
which reduces the percentage of carbon in the mixture
as carbon dioxide is produced
what is the property of aluminium which makes it more suitable for overhead cables than copper?
aluminium is low density
How can you tell that copper is a transition metal and aluminium is not a transition metal for their position in the periodic table?
copper is in the central block in the periodic table
whereas aluminium is in group 3
What is an alloy?
a mixture of metals
explain why the need for copper will cause a problem in the future
as we are running out of copper ores
suggest ways society could overcome the problem that copper ores are running out
use low grade copper ores- from phytomining/bioleaching
reuse/recycle copper
use other materials instead
what is meant by a smart alloy?
an alloy that can return to its original shape when heated
Name the element that is removed from ores when they are reduced
oxygen
how is iron ore reduced in a blast furnace to make iron?
the iron ore is heated
carbon in the air reacts with oxygen in the ore - displaces the oxygen
Explain why copper from areas that contain a very low percentage of copper compound is not extracted by smelting
land contains very little copper
uneconomical
What happens to copper ions during electrolysis?
copper ions are attracted to the negative electrode
where they are reduced (gain 2 electrons)
copper metal is formed
