C10.3 - 10.4 - Extraction of metals and their uses Flashcards
Why is carbon used to extract metals from their ores
Metals that are less reactive than carbon can be extracted from their oxides by reducing.
Carbon is used as it is cheap and abundant
Elements below carbon in the reactivity series can be obtained via
heating their oxides with carbon
Zinc oxide + carbon ==> zinc + carbon dioxide
2ZnO + C ==> 2Zn + CO2
This is a displacement reaction as zinc has been reduced and carbon has been oxidized
Why can’t potassium and aluminum be extracted via carbon
because they are more reactive than carbon
Why don’t we extract silver, gold and platinum via carbon
they are either found as natural pure elements or they can be extracted via heat directly in air
How can metals be extracted that are more reactive than carbon
via electrolysis
But is very costly and expensive
What is the name of the main ore of aluminum
bauxite
What is the main ore of iron
haematite
How is iron extracted from its ore
via a blast furnace
What are the steps of the extraction of iron from a blast furnace
- Hematite (iron ore), coke (impure carbon) and limestone are added to the top of the furnace
- Hot air is blasted from the bottom of the furnace
- Oxygen reacts with coke to form CO2
O2 + C ==> CO2 - More carbon reacts with CO2 to form carbon monoxide
CO2 + C ==> 2CO - The carbon monoxide reacts with iron ore to form iron. The carbon monoxide is a reducing agent.
Fe2O3 + 3CO ==> 2Fe + 3CO2 - Molten iron runs to the bottom and is collected
Why is limestone used in the extraction of iron ore and how does it work
to remove the impurities in the iron like sand
Limestone ==> calcium carbonate
It decomposes in heat
CaCO3 ==> CaO + CO2
Calcium oxide reacts with sand (SiO2) and other impurities to form slag
CaO + SiO2 ==> CaSiO3
Molten slag falls at the bottom and collects on the top of the molten iron preventing the iron from being re-oxidized
What materials come out of the blast furnace in the extraction of iron
slag
Pure iron
