Kuliah Non Fe 8 Mei 2008

Gold

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Gold metal is also extracted from the rocks of the Earth.Large quantities of gold bearing rock are mined from deep mines.Again, the rocks are crushed to make extraction possible.

1.Cyanide solution is added to crushed gold bearing ore to dissolve the gold and leave the unwanted rockbehind.

2. Excess Zinc metal is added to theCyanide and gold solution. The gold precipitates out and sinks to the bottom of the liquid.The zinc/cyanide solution is left behind.

4. 3.Excess zinc metal is dissolved into the solution by adding sulphuric acid.Only the gold metal is now left behind as a solid.

The heavy gold metal is filtered from the liquid.It is dried, then melted. The molten gold is poured into moulds to cool into rough gold plates for electrolytic refining.

DRAW a diagram to show the different types of atoms and molecules that are present at each stage of the process of extraction of gold from its ore.

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Metal Price in Rand/tonne

Gold

Silver

Copper

Tin

Zinc

Chemical symbol

Cu

Au

Ag

Sn

Zn

DISCUSS possible reasons for why different metals cost different prices.

Aluminium Al

Lead Pb

13,000

16,000

110,000,000

4,400

1,700,000

41,000

7,500

Iron (steel) Fe 450