metals and their extractions Flashcards
what is metal extraction
metals are extracted from ores which are rocks containing metal compounds found in the earths crust
these metals can be extracted using chemical reactions
what is the relationship between metal reactivity and extraction
the more reactive the metal is the more stable its metal compound so the harder it is ti extract the pure metal
what are the extraction processes depending in the reactivity series
electrolysis - for metals more reactive than carbon
reduction with carbon - for metals less reactive than carbon (cheap process and is favoured over electrolysis)
metals less reactive than hydrogen are found pure in their native form
what is a displacement reaction and how is it useful
when a more reactive metal displaces a less reactive metal from a compound
they can be used to investigate the relative reactivities of metals
what is oxidation
gain of oxygen
loss of electrons
loss of hydrogen
the species oxidised is known as the reducing agent
what is reduction
loss of oxygen
gain of electrons
gain of hydrogen
the species reduced is known as the oxidising agent
what are the reactions involved in the extraction of iron in a blast furnace
the process is a reduction process
coke reacts with oxygen in the air to form carbon dioxide (exothermic combustion reaction)
C + O2 —> CO2
the carbon dioxide reacts with more coke to form carbon monoxide (the carbon is reduced)
CO2 + C —>2CO
the iron oxide reacts with the coke or carbon monoxide and is reduced to form molten iron
3CO + FE2O3 —>3CO2 +2FE
how are impurities remove from the iron ore in a blast furnace
The main impurity in the mixture is silicon dioxide (sand)
Limestone and those thermal decomposition in calcium oxide
The calcium oxide reacts to silicon dioxide to from solid calcium silicate which can be removed from the furnace
this is a neutralisation reaction
how does electrolysis work
When metallic compounds is melted or dissolved ions are free to move within the liquid or solution
passing a current through the molten liquid or solution means that their solution can be broken down into elements
during electrolysis the substance being broken down is the electrolyte
what are the properties and uses of iron
malleable
an alloy, steel, can be forged from iron and carbon
steel is harder and stronger than iron and is less likely to rust
used to build cars and used in the construction industry
what are the properties and uses of aluminium
low density
light weight for its size
resists corrosion due to very thin layer of oxides on the surface
used in aircraft, trains, overhead power cables, saucepans and cooking foil
what are the properties and uses of copper
good conductor of electricity and heat
soft, easily bent and shaped (malleable)
resistant to corrosion (very unreactive)
used in electrical wiring, gas and water pipes, and plumbing in houses as copper does not react with water
what are the properties and uses of titanium
low density
light weight for its size
resists corrosion
used in fighter aircraft, artificial hip joints and pipes in nuclear power
what are the general properties of transition metals
high melting points
form coloured compounds
have the ability to form ions with different charges
most are malleable and ductile
good conductors of both heat and electricity due to their delocalised electrons
hard
less reactive than alkali metals ( group 1 metals )
what is the test for metal ions
when sodium hydroxide (NaOH) is added:
copper (II) ions give a blue precipitate
iron (II) ions give a green precipitate
iron (III) ions give a brown precipitate
what is an alloy
a substance made of a mixture of 2 or more elements, of which at least one is metal
they are made by mixing molten metals
the composition of alloys can be changed to produce alloys with desired properties
explain what happens during the electrolysis of water
Electrolysis can be used to separate water into hydrogen gas and oxygen gas
positively charged hydrogen ions move to the negative electrode and gain electrons in a reduction reaction
negatively charged hydroxide ions move to the positive electrode and lose electrons to form water and oxygen in oxidation reaction
what are the half equation in the electrolysis of water
at the cathode the equation is 2H+ + 2e- –> H2
at the anode the equation is
2OH- –> O2 + 2H+ + 4E-
Explain what happens during the electrolysis of aqueous solutions
An ionic solution contains the irons that make up the ionic compound and the ions in water (OH- and H+)
at the cathode hydrogen is produced unless the positively charged ions in the ionic compound are from a metal less reactive than hydrogen than this metal will be produced it instead
at the anode, oxygen will be produced unless the ionic compound contains halide ions (Cl-, Br-, I-) in this case the halogen will be produced
what are the electrode equations in the electrolysis of copper (II) chloride
At the cathode cup is less reactive than hydrogen copper ions are reduced to solid copper:
Cu2+ + 2e- –> Cu
At the aloe chloride ions are oxidised:
2Cl- –> Cl2 + 2e-
What are the electrode equation in the electrolysis of sodium chloride
At the cathode hydrogen ions are reduced as sodium is more reactive than hydrogen
2H+ + 2e- —> H2
at the anode chloride ions are oxidised:
2Cl- –> Cl2 + 2e-
what are the uses of electrolysis
Electroplating – covering the surface of one met up with another matter
Example: jewellery coated in silver to make it silver plated
manufacture of copper
Manufacture of sodium hydroxide, are you on gas and chlorine gas
what factors must be considered when extracting metals
Site of extraction plants:
Good infrastructure, close to power station, near a city as a source for workers, away from built-up areas due to noise and pollution
The method used – reduction with carbon can be used where possible to lower energy and cost needed
Recycling – Using recycling plant to recycle and reuse material as opposed to extract new raw materials
why is aluminium oxide dissolved in molten cryolite
Alumina (aluminium oxide) dissolves in molten cryolite at a
temperature much lower than its melting point, therefore
saving energy
