Essay on Chemistry Notes

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Chosen Metal: Gold
Symbol: Au
Atomic Number: 79
Atomic Weight: 196.966569
State at Room Temperature: Solid
Group Name: Transition Metal
Melting Point: 1064o C

a) The uses of the metal you choose and explain how these relate to its properties. One of the main uses of gold, is for jewellery. Gold's properties make it perfect for manufacturing jewellery. It's high lustre, desirable bright yellow colour, tarnish resistance, ductility and malleability are all contributing factors as to why gold is used for jewellery. It's low abundance on earth also means that it has a high economic value, which makes it more desirable. In some cases, gold can be used to make wiring. As well as being a magnificent conductor of electricity, gold is highly ductile. Just one kilogram of gold could be drawn out 5 kilometers to about the thickness of human hair. Components of your computer or laptop, also contain gold. It's ability to conduct electricity allows it to be used for components such as memory chips inside your laptop, or computer. Gold can also be used through dentistry as an alloy to make teeth fillings. It's corrosion resistance allows it to be used in teeth so that food acids don't cause corrosion. b) Name the ore from which the metal you chose is extracted. Research the abundance and ease of extraction of the ore on our Earth. Since gold is such an unreactive metal, it is usually found in its uncombined and elemental form. Gold is mostly found as tiny specks in alluvial deposits (which is basically soil and sedimentary rock), but is occasionally found as large nuggets. Although gold is mostly found in its elemental form, it can also be found naturally alloyed with silver (called electrum) or sometimes even with mercury (called amalgam), and uncommonly with Tellurium (called Calaverite or gold telluride). Since gold is mostly found in its elemental form, extracting it is not a difficult task, and can be done by hand through panning. As gold is much denser than rock, it will settle to the bottom of a pan when shaken and submerged in water. As well as panning, open cast mining is used to extract gold. This just means that large layers of surface rock are removed by machines so that the layers below where gold is more prevalent are easier to access. When gold is found in its combined state, the most common method of extraction is called cyanidation. In this process, the ore is crushed and then cyanide solution is added so that the gold particles are chemically dissolved from the ore. During this, gold is oxidised. Zinc dust is added so that it takes the place of gold, and the gold is precipitated out of the solution. Gold's abundance in our lithosphere is around 0.004parts per million. c) Describe the recycling process of the metal you chose in Australia and explain why it is preferred rather than extracting from our Earth. The first step during the process of recycling gold, is the collection. Unwanted items such as jewellery, old gold watches, gold wires/chains and electronic fittings are all types of things that are collected during this process. After this, the materials are sorted. As with any recycling process, this step must be undertaken as to determine what percentage of the materials contain gold. Once all the components have been sorted, they are ready to be smelted. The second step is known as smelting. This is where gold is heated past its melting point so that it can be separated from any impurities with different melting points. At the boiling point of gold, it is possible for smelters to separate other impurities, that are used in previous gold-hardening processes, nitric acid is used to obtain pure gold. The metals are then separated and gathered in a sludge. The gold that cools off is considered 24 carat pure gold. These bars and chips are weighed so that they can be accurately priced and given an economic value. Gold is recycled for many reasons. It is beneficial for both the
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