B-+Block+Rusting

==Rusting:== , A reddish- or yellowish-brown flaky coating of iron oxide that is formed on iron or steel by oxidation. in the presence of moisture

Fe+3O2+6H2O-->4Fe(OH)3
Iron is the most commen element (by mass) forming the planet earth as a whole.It is exothermic and in a nuclear fusion reaction it is also the first sandwitch compound discoverd.Iron is the mettal used at the active site of the important redox of enzymes dealing with celluar resperation in oxidation and reduction of plants and animals.Oxygen is the most abontant element by mass in the earths crust making up almost half of the earth's crust.Elemental oxygen is produced by cyanobacteria algie in plants it is used for life support systems in air crafts submariens.Free elemental O2 only beggin to accumulate in atmosphere about 2.5 billion years ago.

Hydrogen most abondent chemical substanes.Natrual accuring atomic hydrogen is rare on earth becuse hydrogen readily forms of covalent compounds with most elements.Hydrogen gas was first artifically produced in the early 16th century by mixing of metals and stron acids.

.In the 19th century iron was used in bridges and buildings because it was one of the stronges metals at the time but they had to think of how it would hold when it came in contact with water.

"A team of scientiest working with the Ecole polytechnique Federale de lausanne (EPFL)now claim that they have developed a new technology witch makes it possible for solar farms to store the light energy they collect during day time in the form of hydrogen.The idea is converting solar energy into  hydrogen is not a new one resurchers have been working on it for more than 4 decades.The photoelectrochemical (PEC)tandem solar cell a technic for  producing hydrogen directly from water.Thats why iron oxide used by the team is a bit for devoleped then what you find on an old nail.Semi conducter,  performes the oxygen of illusion reaction is just iron oxid "its a stable and a abundant material.there is no way it will rust any further!but its one of the worst semi conducters avaliable [] ".

 Changes you observe in the universe around you are caused by chemical reactions one of the chemical reactions is salt this is formed by sodium cloride its uses are soda ash, water softening, road salt, but its most common use is in the food ind.Chemical reaction's is a process that leads t the transformation of one set of chemical subtanses to another.Normaly chemical reactions enconpass changes that stricly involve the motin of electrons in the forming and breaking of chemical bonds.They ca [] n often be http//actu.epfl.ch/news/using-rust-and-water-to-store-solar-energy-as-hydr described by a chemical equation.