alumini

 Universidad veracruzana
Facultad de ingeniería
Química general
Aluminum
Nombre del docente: Emilio Vásquez Nava
Nombre de los estudiantes: Arguelles

Veracruz, Vera, 03\11\2013

Tabla de contenido




INTRODUCTION

The chemical element aluminium (symbol Al) is a metal, which in its pure, bulk form is relatively soft, light and abundant -8.07% of the Earth’s crust compared, for example, with the familiar metal iron at 5.06%. Only oxygen and silicon (as sand) are more abundant in the Earth’s crust, and yet it was only a century ago that aluminium was discovered as the most common of metals. We are all familiar with the bronze and iron ages that considerably predate the discovery of aluminium - so why was aluminium so late inappearing on the scene? The answer, as for the pre-historic copper and bronze ages (bronze is a metallic mixture of copper and tin) and later iron and steel (a mixture of iron and a small quantity of carbon), relates to man’s technological capability not only to extract the material from the Earth’s crust but also to process the material into a useful product.
The great affinity of oxygen foraluminium (which produces a chemical compound, alumina Al2O3) means that the element aluminium is present in the Earth’s crust incorporated in a mineral, Bauxite ore. The technical challenge at the end of the last century was to extract aluminium metal from Bauxite. The solution - the “Hall – Héroult” process - was the development of an electrolytic process, which is still used today. A large quantityof electricity is required, and it was the development of cheaper electricity (particularly hydroelectric power) at the turn of the last century, that made the industrial production of aluminium a commercial proposition. The incentive to recycle aluminium is considerable because, compared with the energy required for primary electrolytic extraction, only a few percent of that energy level isrequired to remelt scrap material. Nonetheless, as a general rule, aluminium is more expensive than steel; hence, for a given application, the selection of aluminium over steel (or any other competitive material) will rely upon one or more of the many attributes of aluminium which make it a better choice for a particular application. Lightness in weight, the characteristic to be readily formed intouseful shapes, good corrosion resistance, and high electrical and heat conductivities are just some of the potentially valuable attributes.


DISCOVERY OF ALUMINUM
People have used alum since ancient times for dyeing, tanning and to stop bleeding. Alum is potassium aluminum sulfate.
In the 1750s German chemist Andreas Marggraf found he could use an alkali solution to precipitate a newsubstance from alum. Marggraf had previously been the first person to isolate zinc in 1746.The substance Marggraf obtained from alum was named alumina by French chemist Louis de Morveau in 1760. We now know that alumina is aluminum oxide – chemical formula Al2O3De Morveau believed alumina contained a new metallic element, but, like Marggraf, he was unable to extract this metal from its oxide.
In 1807or 1808, English chemist Humphry Davy decomposed alumina in an electric arc to obtain a metal. The metal was not pure aluminum, but an alloy of aluminum and iron. Davy called the new metal alumium, then renamed it aluminum. 
Aluminum was first isolated in 1825 by Hans Christian Ørsted (Oersted) in Copenhagen, Denmark who reported, “a lump of metal which in color and luster somewhatresembles tin.”Ørsted produced aluminum by reducing aluminum chloride using a potassium-mercury amalgam. The mercury was removed by heating to leave aluminum.
German chemist Friedrich Wöhler (Woehler) repeated Ørsted’s experiment but found it yielded only potassium metal. Wöhler developed the method further two years later, reacting volatalized aluminum trichloride with potassium to produce small amounts of...