Metals Flashcards
Reaction with water: Mg Al Zn Fe
Very slow reaction with cold water. React when heated in steam producing an insoluble metal oxide and hydrogen
Reaction with water: Cu Ag Au
No reaction with water or steam
How do you find the reactivity of cobalt
Get 5 test tubes and add cobalt nitrate
Then add magnesium, zinc, silver, iron and copper
If the metal is more reactive than cobalt then the element will begin to form on the surface of the metal
If no reaction occurs the metal is less reactive
What’s an ore
A mineral containing a metal compound from which the metal can be economically extracted
What are the three stages involved in extracting metals
Mining the metal ore and concentrating it
Conversion of the metal ore into the metal
Purification of the metal
What is aluminium extracted from
Bauxite (impure aluminium oxide)
Give four metals that cannot be extracted from their ore by reduction with carbon or carbon monoxide
Potassium sodium lithium and magnesium
How are potassium sodium lithium and magnesium extracted
By passing an electric current through a molten compound, which splits it up into the original elements (electrolysis)
What is the main ore of iron
Haematite (iron (|||) oxide)
How is iron extracted from its ore
The ore is grown up
It is mixed with limestone and coke
This is added to the top of the blast furnace
Air (preheated to 600 degrees Celsius) is injected into the furnace through pipes
Molten iron is tapped from the lower tap hole (slag is tapped from the higher one)
The process is continuous
Name four substances (raw materials) that go into the blast furnace
Iron ore (Fe2O3)
Coke (treated coal)
Limestone (CaCO3)
Air (O2)
Name three substances that come out of a blast furnace
Molten iron
Molten slag
Waste gases
What happens at the bottom of a furnace
Coke reacts with oxygen in the hot air
C + O2 = CO2
This reaction is exothermic
What does the heat produced during the reaction with coke and oxygen do
Decomposes limestone forming calcium oxide and more carbon dioxide
CaCO3 = CaO + CO2
What happens when carbon dioxide works it’s way up the furnace
It is reduced to carbon monoxide at about 1500 degrees Celsius by reaction with more coke
CO2 + C = 2CO
What is the main reducing agent in the blast furnace
Carbon monoxide, it reduces the haematite to iron at about 600 degrees Celsius and producing carbon dioxide
Fe2O3 + 3CO = 2Fe + 3CO2
What is the main purpose of the limestone in a blast furnace
To remove impurities. These are mainly silica which, if left in the iron, would make it brittle and so they react and are neutralised at about 900 degrees Celsius by a basic oxide (formed by the thermal decomposition of limestone) to form slag
CaO + SiO2 = CaSiO3
Why does the molten slag sit on top of the molten iron
It is less dense, and it is to prevent the reoxidation of the iron by preheated air
Why is the iron from the blast furnace not very useful
It has a high concentration of carbon impurities and is very brittle
Why is pure iron not useful
It is very soft and stretches easily and is less brittle than cast iron; it also rusts easily
What is an alloy
A mixture of metals or of a metal and carbon
What two substances are needed for iron to rust
Water and oxygen (iron (|||) oxide)
Rust prevention methods
Paint (cars)
Grease (bicycle chains)
Plastic (chain link fence)
What is sacrificial protection
When a block of metal more reactive than iron (eg zinc) is added to the iron. So it will corrode before the iron does
What is galvanising
When iron is protected from rusting by dipping the iron into molten zinc so that the iron is completely coated. It is used for dustbins and buckets
Where are transition metals in the periodic table
The central block
Mild steel
Malleable
Used in car bodies chains and pylons
Hard steel
Hard and strong
Used in chisels files saws and razor blades
Stainless steel
Does not rust
Used in cutlery kitchen sinks sculptures and surgical instruments
Titanium steel
Low density high strength does not rust
Used in the edges of high speed cutting tools, armour plating, darts viola strings and golf clubs
Equation for the reaction at the cathode
3+ _
Al + 3e = Al
Equation for reaction at anode
2- + -
2O = O2 + 4e
What are the anode and cathode made of
Graphite
Where is the cathode in an electrolytic cell
At the bottom, below the molten aluminium
Why does the anode need frequent replacement
At 1000 degrees Celsius the graphite anodes burn away in the oxygen to give carbon dioxide
Why is cryolite added in the electrolyte
To reduce the operating temperature of aluminium from 2000-800 degrees Celsius and when it is molten it acts as a solvent for the alumina
What kind of melting points and boiling points do metals have
High
What kind of melting and boiling points to non metal as have
Low unless they have a giant covalent lattice structure
reaction with water: K Na Li Ca
React with cold water giving soluble metal hydroxide and hydrogen
