La Casa De Bernarda Alba

* Oxide ions get attracted to the anode and discharged (oxidation); 2O2-, 4e → O2 Aluminum ions get attracted to the cathode and discharged and settle at the bottom
of the container (reduction); Al3+ + 3e → Al
* Oxygen gas evolves and is collected with waste gases
* Aluminum is sucked out of the container at regular intervals
Oxygen gas which evolves reacts with carbon from the cathodeforming CO2. The cathode gets worn away. To solve this, the cathode is replaced at regular intervals. Heat supply is very expensive; this is why cryolite is used to decrease the melting point of aluminum oxide and this process is done in plants which use hydroelectric energy because it is cheap.
 
Uses of aluminum:
* Construction of air-craft bodies because aluminum is very strong and verylight and it is resistant to corrosion
* Food containers because it is resistant to corrosion
* Overhead power cables because it conducts electricity, is very light, malleable and ductile. Although it is strengthened with steel core
 
Extraction of Iron:
The ore of iron is called hematite. It consists of 60% iron in form of Iron oxide (Fe2O3) with other impurities such as silicon
oxide(SiO2). This process takes place in a tower called a Blast furnace.
Substances | Products and Waste Materials |
 Iron ore (Hematite)  Coke (heated coal)  Lime stone (Calcium carbonate)  Hot Air |  Pure Iron  Carbon dioxide  Air  Slag (Calcium silicate) |
* Substances are put in the blast furnace
* The process starts by blowing in hot air at the bottom of the furnace* Coke burns in oxygen from the hot air producing carbon dioxide; C + O2 → CO2
* Heat makes lime stone decompose into calcium oxide and carbon dioxide; CaCO3 → CaO + CO2
* Carbon dioxide produced goes up the furnace and reacts with more coke up there producing
carbon monoxide; CO2 + C → 2CO
* Carbon monoxide is a reducing agent. It rises further up the furnace where it meets ironoxide and starts reducing it producing iron and carbon dioxide; Fe2O3 + 3CO → 2Fe + 3CO2
* Calcium oxide which was produced from the thermal decomposition of lime stone is a base. It reacts with impurities of hematite such as silicon oxide which is acidic forming calcium silicate which is called slag; CaO + SiO2 → CaSiO3
* Molten Iron and slag produced trickles down and settles at thebottom of the furnace. Iron is denser than slag so it settles beneath it.
Iron and slag are tapped off separately at regular intervals and pure iron is collected alone
* Waste gases such as carbon dioxide formed in the process and nitrogen and other gases from air blown in escape at the top of the furnace.
 
Conversion of Iron into Steel:
Iron produced in the blast furnace is called pig iron.It contains 4% carbon as well as other impurities such as sulfur, silicon and phosphorus which make it hard and brittle. It got that name from the fact that it has to be poured into mould called pigs before it is converted into steel. Most of produced iron is converted into steel because steel has better properties.
Making steel out of pig iron is a process done in a basic oxygen furnace:
*Molten pig iron is poured into the oxygen furnace
* A water cooled lance is introduced which blows oxygen onto the surface of the molten iron
* Impurities start to react
* Carbon is oxidized into carbon monoxide and carbon dioxide and escape
* Sulfur is oxidized into sulfur dioxide and escapes
* Silicon and phosphorus are oxidized into silicon oxide and phosphorus pentoxide whichare solids.
* Calcium oxide (lime) is added to remove the solid impurities as slag which is skimmed off the surface
* Throughout the process, sample of the iron are being taken and analyzed for the percentage of carbon present in it. When the percentage of carbon desired is reached, the furnace is switched off and the steel is collected.

There are many different forms of steel.  Each...