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  • Level: GCSE
  • Subject: Science
  • Essay length: 3747 words

Gold. For thousands of years, gold has been regarded as the finest and most precious metal known to man. In this CDA, I will try to find out why gold is so valuable.

Extracts from this essay...

Introduction

GOLD Uttam Sharma Centre-Devised Assessment For thousands of years, gold has been regarded as the finest and most precious metal known to man. In this CDA, I will try to find out why gold is so valuable. Gold INTRODUCTION PROPERTIES Gold is a metal which has had many purposes over the thousands of years. It has been used for jewellery, money, decoration and, more recently, in tooth fillings and electronics. It's a soft, yellow, metal with useful thermal and electrical properties. Unlike other metals like silver and copper, gold does not tarnish over time and use. Tarnish is a dark layer which forms over some metals such as copper, brass and aluminium. It is very dense metal, at 19.32 g/cm3. To give you an idea of just how heavy gold is, think of it this way: the mass of 1 litre of water is 1 kilogram. The mass of 1 litre of gold is 19.32 kilograms. Imagine carrying a 1-litre water bottle that weighs over 3 stone. The colour of gold is also called gold. It has an atomic number of 79, and a relative atomic mass of 196.97. The symbol for gold is Au, which comes from the Latin word for gold, 'aurum'. A gold leaf is gold that has been beaten into very thin sheets. Of all elements, gold is the most malleable and ductile. 1 gram of gold can be beaten down to cover an area of 1 square metre. Malleability is the ability of a material to be flattened down into a thin sheet by rolling or hammering. Also, because of its high ductility, solid gold wire can be anything up to around one hundredth of a millimetre thick. Ductility is the extent to which a material can be deformed (made out of shape) to, without fracture. One of the main reasons why gold is so admired by people around the world for thousands of years is because it's highly unreactive.

Middle

9k gold is often said to be a harder metal than 18k gold. Well, since gold is a soft metal, 9k gold allows more of the content to be composed of other, harder metals; unlike 18k gold where there's less space (percentage) for other, harder metals. But this is not true. The hardness of the gold alloy depends on other factors such as how the material was treated during manufacture. Colour of the gold alloys with their karatage Percentage of metals that are present in different gold alloys (%) Gold Copper Silver Zinc Cadmium Platinum Palladium Nickel Iron Aluminium Yellow 22k 91.67 2.00 5.00 1.33 Red 18k 75.00 25.00 Rose 18k 75.00 22.25 2.75 Pink 18k 75.00 20.00 5.00 White 18k 75.00 Platinum or palladium 25% White 18k 75.00 5.00 10.00 10.00 Grey-white 18k 75.00 8.00 17.00 Soft green 18k 75.00 25.00 Light green 18k 75.00 23.00 2.00 Green 18k 75.00 5.00 20.00 Deep green gold 18k 75.00 6.00 15.00 4.00 Blue 18k 75.00 25.00 Purple 19.2k 80.00 20.00 White 9k 37.50 62.50 Rich yellow 9k 37.50 31.25 31.25 Pink 9k 37.50 42.50 20.00 Red 9k 37.50 55.00 7.50 Note: the shaded areas indicate 0% usage of that metal in the specific alloy OTHER USES OF GOLD Today gold is used everywhere around you. Gold is an excellent conductor of electricity and doesn't corrode or tarnish. It can also work at very high temperatures. This makes it ideal for use in electronics. It is the best metal to use in for small electronic contacts, switches and other components. These electronic parts can be found in computers, TVs and telephones. Because of gold's high price, only a very thin film of gold is used for gold-plated contacts. Also, gold has often been used for many years as the reward for highest achievement at the Olympics and other major sporting events like the FIFA World Cup. In reality, the 'gold medal' in the Olympics is actually a medal made out of silver, but plated in gold.

Conclusion

My results could have been more valid if I'd gone to other streets and asked them the same questions, since the people I asked are from around the same wealth group (I assume this because all of the houses in the street are around the same size) and results may have varied minutely or greatly if I tried other people. Also, in order to increase reliability, I should have asked more people about their opinion and knowledge of gold. This would've given me more accuracy in my results. This would be because as I would be asking more and more people, my results would be forming more and more into results which represent the population of UK. Of course, I couldn't ask all of the country and also no matter how many people I asked (up until the point where I'd asked everyone in the country), my results weren't going to represent the entire population. In conclusion I have learned a lot about gold during my research. I now understand its importance to this world both aesthetically and chemically. I can also conclude, by looking at my results, that people do not know much about gold. When I asked question 6 for example, people were bewildered by that fact and seemed somewhat shocked. They were quite surprised to know that most 'gold' jewellery in the UK consists of less than 50% of gold itself. GLOSSARY - Alloy - when two or more metals are combined to make an alloy which shares some of the characteristics of its constituent metals. - Metallurgy - the study of metals. - Ductility - the ability to be made into wire without fracture. - Malleability - the ability to flatten a metal down into a thin sheet. - Tarnish - layer of corrosion that forms over metals such as copper and zinc, but not gold, since gold doesn't easily oxidise. - Corrosion - deterioration of metals caused by oxidation or other chemical reactions.

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