Transcript Metals - Miss Emms

Metals
Learning Objectives
• Use reactivity data to determine a
reactivity series
• Relate extraction method to reactivity
of metals
• Write word/symbol equations for
reduction of metal ores with carbon
Put the metals in order of reactivity
Metal
A
B
C
D
E
Reaction with
dilute acid
Reaction
with water
Reaction
with oxygen
Some reaction
Slow reaction
Burns brightly
No reaction
No reaction
Reacts slowly
No reaction
No reaction
No reaction
Violent reaction Slow reaction
Burns brightly
Slight reaction
Reacts slowly
Reacts with
steam only
Displacement reactions
A displacement reaction is one where a MORE REACTIVE metal will
DISPLACE a LESS REACTIVE metal from a compound.
Magnesium
Copper sulphate
Mg
Cu
The magnesium
DISPLACES the copper
from copper sulphate
Mg
SO4
Magnesium sulphate
Cu
Copper
SO4
The Thermite reaction
Al
Fe
O
Aluminium
Iron oxide
Aluminium DISPLACES
iron from iron oxide
Simplified and
NOT balanced
equation
Pie chart to show the elements
present in the earth’s crust
Most elements in the earth’s
crust are found as compounds
Compounds contain atoms of more than 1
element ---------- joined together.
There are 2 types of chemical ---IONIC bonds are formed between a metal
+ non metal. The metal atom TRANSFERS
electrons to the non metal.
COVALENT bonds are formed between non
metals. The atoms SHARE electrons.
Extraction methods
Potassium
Increasing reactivity
Sodium
Calcium
Magnesium
Metals ABOVE CARBON, because
of their high reactivity, are
extracted by ELECTROLYSIS
Aluminium
Carbon
Zinc
Iron
Metals BELOW CARBON are
extracted by heating them with
carbon in a BLAST FURNACE
Tin
Lead
Gold
These LOW REACTIVITY metals don’t
need to be extracted because they are
SO unreactive you’ll find them on their
own, NATIVE (not in a metal oxide)
Platinum
N.B. Cu can sometimes be found native
Copper
Silver
Native metals
Unreactive elements
(Gold, silver and
sometimes copper)
do not need to be
extracted as they
are not chemically
combined with any
other elements.
Iron
Magnetite
Magnetite (iron
oxide Fe3O4)
Hematite (iron oxide, Fe2O3)
Metal ores
• Minerals in rocks are not pure, but mixed with
other substances.
• To be useful the metal needs to be extracted
from the rock.
• A metal ore is a rock containing enough of the
metal compound to make it economic to extract
it.
• This can vary over time as demand/ supplies/
value change.
The Blast furnace
Raw materials added
Waste gases escape
Coke
Limestone
Iron ore
Oxygen
Hot air
Molten IRON
Molten SLAG
Reduction with carbon
• Zinc, iron, tin, lead and copper can all be extracted from
their ores by SMELTING.
• Metal ore (OXIDE or SULFIDE) is heated to a high
temperature with carbon.
• Carbon DISPLACES the metal.
• This is a REDOX process, the carbon is OXIDISED
(gains oxygen) at the same time the metal ore is
REDUCED (loses oxygen)
Equations
From an oxide:
Iron oxide + carbon carbon dioxide + iron
(Fe2O3)
2Fe2O3 + 3C  3CO2 + 4Fe
From a sulfide:
Copper sulfide + oxygen  sulfur dioxide + copper oxide
(CuS)
2CuS + 3O2 2SO2 + 2CuO
Copper oxide + carbon  carbon dioxide + copper
(CuO)
2CuO + C  CO2 + 2Cu
Summary:
Extracting metals
1) What is an ore?
2) In what form are metals usually found in the Earth?
3) How do you get a metal out of a metal oxide?
4) What is this type of reaction called?
Type of metal
High reactivity (i.e
anything above carbon)
Middle reactivity (i.e.
anything below carbon)
Low reactivity
Extraction process
Examples