UNIT 3 - METALS Flashcards
WHAT IS A METAL ORE ?
A metal ore is rock from which metals are obtained
Metals can be extracted using chemical reactions
WHAT IS MEANT BY NATIVE ?
An uncombined metal (gold) nonreactive
As metals become more reactive they become harder to extract
WHAT HAPPENS IN A REDOX REACTION ?
Both reduction and oxidation
In reduction -
Gain of electrons or removal of electrons
In oxidation -
Addition of oxygen or loss of electrons
OIL RIG
WHAT IS A DISPLACEMENT REACTION ?
Used to extract metals from ores
A more reactive metals is used to displace a less reactive metal from a compound
DESCRIBE THE BLAST FURNACE PROCESS
Iron can be extracted by heating it with carbon
The carbon is heated and reacts with oxygen in the air to form CO2
CO2 reacts with more oxygen to form CO
CO is an excellent reducing agent
It reduces the iron oxide into iron and CO2
Limestone breaks down in the heat to form calcium oxide
Calcium oxide reacts with impurities to form slag
Slag is lighter than molten iron so floats to the top where it can be removed
WHAT GOES INTO THE BLAST FURNACE ?
Iron Ore
Coke - Source of carbon / fuel
Limestone
Hot air
WHAT IS CREATED IN THE BLAST FURNACE ?
IRON
SLAG
CO2
WHAT IS THE COMBUSTION REACTION IN THE BLAST FURNACE ?
C = Coke
C + O2 —-> CO2
CO2 + C —–> 2 CO
Coke reacts with oxygen to form CO2
The CO2 reacts with more carbon to form the reducing agent CO
WHAT IS THE REDOX REACTION IN THE BLAST FURNACE ?
Fe2O3 + 3 CO —-> 2 Fe + 3 CO2
Iron is reduced by Co (Lost Oxygen)
CO is oxidised (Gains Oxygen)
WHAT IS THE THERMAL DECOMPOSITION REACTION IN THE BLAST FURNACE ?
CaCo3 ——> CaO + CO2
Limestone breaks down in the heat to form CO2 and calcium oxide
WHAT IS THE NEUTRALISATION REACTION IN THE BLAST FURNACE ?
CaO + SiO2 —–> CaSiO3
Calcium Oxide reacts to silicon dioxide to form slag
WHAT IS ELECTROLYSIS ?
The breaking down of ionic compounds using electricity
WHAT IS AN ELECTROLYTE ?
The molten compound
WHAT HAPPENS IN ELECTROLYSIS ?
The ions in the molten metal compound are free to move
positive Pb 2+ ions are attracted to the negative cathode where they gain electrons and are reduced to form lead
Negative Br- ions are attracted to the positive anode where they lose electrons and are oxidised to form bromine
WHAT KIND OF POWER SUPPLY IS USED IN ELECTROLYSIS ?
D.C.
WHAT IS THE NAME OF THE ALUMINIUM ORE ?
BAUXITE
WHY IS CRYOLITE ADDED TO THE ALUMINIUM ORE ?
It lowers the melting point
Otherwise it would be too costly and require too much energy
HOW DOES INDUSTRIAL ELECTROLYSIS DIFFER FROM ELECTROLYSIS ?
The cathode is the container itself
Anodes are dipped into the container
Anodes are made form carbon
Cryolite must be added
DESCRIBE ELECTROLYSIS OF ALUMINIUM OXIDE ?
Cryolite is added to lower the boiling point
The molten ore is then placed in the container
Al 3+ positive ion is attracted to the negative cathode and gains electrons
Goes from ion to atom
The O 2- ion is attracted to the positive carbon anode and loses electrons
WHY DOES THE CARBON ANODE NEED TO BE REPLACED ?
The carbon reacts with the oxygen producing CO2. This means the carbon anode wears away and needs to be replaced frequently
WHAT IS AN ALLOY ?
A mixture of elements where at least one is a metal
EXAMPLES OF ALLOYS ?
Steel - Iron and carbon
Bronze - Copper and tin
WHY ARE ALLOYS IMPORTANT ?
They have different properties to the metals that made them
i.e. copper and tin are soft but bronze is hard
PROPERTIES OF ALUMINIUM ?
Lightweight, strong, good conductor
Used in aircrafts and drink cans
