2.3 Metals and extraction Flashcards
What are ores?
Ores are raw minerals found in Earth’s crust that contain metal compounds such as Iron Oxide (Fe₂O₃) or bauxite (Al₂O₃).
The more reactive a metal is, the harder it is to separate it from it’s formula.
- Iron is less reactive so you can use a displacement reaction (Reduction reaction) to get a pure metal.
- Aluminium is more reactive and can be separated from it’s compound using electrolysis when molten.
- Gold, platinum and sliver ore are found pure as they are very unreactive.
List the reactivity series.
Potassium- Parry (Most reactive) Sodium- Said Calcium- Cancel Magnesium- Mocks Aluminium- And (Carbon- Car)-Gas Zinc- Zoos Iron- In Tin- The Lead- Lead. (Hydrogen- Harrison)-Gas Copper- Coppen Silver- Sings Gold- Graham's Platinum- Pieces (Least Reactive) ;)
What is the process of extracted iron using a blast furnace?
1) Raw materials including iron ore, coke (carbon) and limestone are added at the top of a furnace.
2) Blasts of hot air are blown in at the bottom of the furnace and the oxygen in the air reacts with coke to form carbon monoxide - this reaction is very exothermic. (2C + O₂ → 2CO)
3) The carbon monoxide rises up the furnace and reacts with iron (III) oxide to form iron (Fe₂O₃ + 3CO → 2Fe + 3CO₂)
4) This molten iron runs out of the bottom of the furnace.
5) It’s either used to make steel or placed into moulds to solidify.
Why is limestone added to a blast furnace?
It’s added to remove any impurities such as sand (Silicon Dioxide)
1) Limestone thermally decomposes to form Calcium Oxide and Carbon Dioxide (CaCO₃ → CaO + CO₂)
2) Calcium neutralises the sand to form slag
(CaO + SiO₂ → CaSiO₃)
Slag can be used in construction and a whole range of tasks.
What is the overall reaction in a blast furnace?
Fe₂O₃ + 3CO → 2Fe +3CO₂
Fe₂O₃ to 2Fe is Reduction
3CO to 3CO₂ is Oxidation
What is electrolysis and what is an electrolyte.
A process where ionic substances (either molten or in a aqueous solution) are split apart using large amounts of electricity.
The electrolyte is the ionic substance being separated.
What is OILRIG
Oxidation Is Loss (of electrons) Reduction Is Gain (of elections)
How is electrolysis used to create pure aluminium?
1) Aluminium oxide is heated (with the assistance of cryolite that lowers the melting point) until it melts.
2) This allows positively charged aluminium ions (Al³⁺) to move towards the negatively charged cathode (at the bottom).
3) The Aluminium ion gains 3 electrons ( Al³⁺ + 3e⁻ → Al) which neutralizes it into a normal atom where it’s filtered out
4) Negatively charged Oxygen (O²⁻) ions are attracted to the anode where it gains 2 electrons (2O²⁻ → O₂ + 4e⁻)
5) The overall reaction is 2Al₂ O₃ → 4Al + 3O₂
NOTE: The graphite anode losses mass over time as oxygen reacts with carbon to form Carbon Dioxide (C+O₂→ CO₂)
What is the chemical formula for a (metal) sulphate?
(Metal)SO₄
What is the purpose of the cryolite in the creation of pure aluminium?
To reduce the boiling boing of aluminium which also reduces the energy needed to start the reaction.
Why does the mass of the anode reduce over time in the formation of pure aluminium?
When the 2O²⁻ carry out oxidation at the graphite anode (2O²⁻ → O₂ + 4e⁻) some O₂ reacts with the graphite (Which is carbon) to form carbon dioxide (C + O₂ → CO₂)
What is the chemical formulae for Slag?
CaSiO₃
What happens in a thermite reaction?
Iron Oxide + Aluminium (+ Heat) → Iron + Aluminium Oxide
Fe₂O₃ + 2Al → Al₂O₃ + 2Fe
This displacement reaction is VERY exothermic.
What is the reaction inside a blast furnace to form carbon monoxide?
2C + O₂ → 2CO
Coke + Oxygen → Carbon Monoxide
What is the reaction inside a blast furnace to form Iron?
Fe₂O₃ + 3CO → 2Fe + 3CO₂
Iron oxide + Carbon Monoxide → Iron + Carbon Dioxide
What is the process of forming slag in the blast furnace?
1) Limestone thermally decomposes to form Calcium Oxide and Carbon Dioxide (CaCO₃ → CaO + CO₂)
2) Calcium reacts with sand to form slag
(CaO + SiO₂ → CaSiO₃)
Slag can be used in construction and a whole range of tasks.
What is slag used for?
Can be used in construction and a whole range of tasks.
What is the chemical formula for sand?
SiO₂ (Silicon dioxide)
What is the general process for electrolysis (Including electron transfer)?
1) Electrolyte substance is separated into its positive and negative ions
2) Positive ions (Cations) are attracted to the negatively charged cathode (e.g. Al³⁺ + 3e⁻ → Al)
The ion GAINS electrons (Reduction)
3) Negative ions (Anions) are attracted to the positively charged anode (e.g. 2O²⁻ → O₂ + 4e⁻).
The ion LOSES electrons to gain a full outer shell (Oxidation).
4) The ionic substance is now slip into neutral atoms.
What is the difference between electrolysis with dissolved salts with reactive metals (e.g. sodium) compared to other electrolysis.
There competition at the cathode between the positive reactive metal and hydrogen ion (from the water). Hydrogen, with no electrons, gains electrons more easily so hydrogen gas is produced. (2H⁺ + 2e⁻ → H₂)
What is the main formula in the electrolysis of water that explains the different water levels in each tube?
2H₂O → 2H₂ + O₂
4 hydrogen compared to 2 oxygen.
What happens at the cathode with the electrolysis of water?
2H⁺(aq) + 2e⁻ → H₂(g)
A reduction reaction
What happens at the anode with electrolysis of water?*
2OH⁻(aq)→ O₂(g) + 2H⁺ + 4e⁻
An oxidation reaction.
(Extra 2 hydrogen- still more hydrogen in the end-2:1 ration)
What elements are added to create stainless steal?
Chromium and Carbon
What are transition metals and their properties?
Metals found between group 2 and 3 (Middle of periodic table)
- Form coloured compounds
- Good conductors of electricity
- Malleable
- Less reactive metals
- High melting points (apart from mercury)
- Varying charges e.g. Fe2+ and Fe3+ or Cu+ and Cu2+
What is an inert electrode?
An electrode that doesn’t react with the electrolyte
What happens at the cathode when electrolysing aqueous solutions of ionic compounds?
If the metal (positive ion) is less reactive than hydrogen (in the reactivity series) then that metal will be formed at the cathode. If it’s more reactive, hydrogen gas will be produced. (2H⁺(aq) + 2e⁻ → H₂(g)) and the metal will remain in the solution.
What happens at the anode when electrolysing aqueous solutions of ionic compounds?
Simple ions (Br⁻, Cl⁻) will form as normal but compound ions (NO₃⁻,CO₃⁻, SO₄⁻) will remain in the solution and hydroxide will instead form oxygen (2OH⁻(aq)→ O₂(g) + 2H⁺ + 4e⁻)
What is brine?
Sodium Chloride solution (Water)
What is the set up for electroplating a material?
Cathode (-)- The object you want electroplated
Anode(+)- Metal you want to code the object with (cathode)
Electrolyte- Solution of the coating metal (E.g. Metal Nitrate or sulfate)
What is the set up for the purification of copper and what happens?
Anode(+)- Impure copper
Cathode(-)- Pure Copper
Electrolyte- Copper (II) sulfate solution
- Once the two rods are charged with a battery, the copper atoms in the anode lose their electrons (Cu → Cu²⁺ + 2e⁻) and become positively charged ions that move to the cathode where they become atoms again (Cu²⁺ + 2e⁻ → Cu)
As a result:
The pure rod increases in mass and the impure rod deteriorates to an ‘anode sludge’.
How do we create sodium hydroxide?
Brine (Sodium Chloride) in an aqueous solution.
Chlorine gas forms at anode and Hydrogen gas at cathode leaving Sodium and hydroxide ions which ionically bond to create sodium hydroxide
This is done on a commercial scale using sea water
Production of:
Soaps
Explosives
paper
dyes
Chemical tests for transition metals ( Fe2+ and Fe3+ or Cu+ and Cu2+)
