Extraction of Metals
Metals are very useful. Ores are naturally occurring rocks that contain metals that are chemically bonded to other elements (like oxygen). For example, iron ore is used to make iron and steel. Copper is easily extracted, but ores rich in copper are becoming more difficult to find.
Aluminium and titanium are metals with useful properties, but they are expensive to extract. Most everyday metals are mixtures called alloys.
Methods of extracting metals
The Earth's crust contains metals and metal compounds such as gold (in it’s native form – uncombined with any other elements), iron oxide and aluminium oxide, but when found in the Earth these are often mixed with other substances. To be useful, the metals have to be extracted from whatever they are mixed with.
The method used to extract metals from the
ore in which they are found depends on their
reactivity. For example, reactive metals such
as aluminium are extracted by electrolysis,
while a less-reactive metal such as iron
may be extracted by reduction with carbon
or carbon monoxide. Thus the method of
extraction of a metal from its ore depends
on the metal's position in the reactivity series.
Extraction of metals; ANSWERS
1. What is an “ore”?
An ore is a naturally occurring rock that contains a metal that is chemically bonded to another element like oxygen.
2. Where are metal ores found?
In the Earth’s crust.
3. What percentage of copper is mined by the USA? Show how you worked it out.
% of copper mined by the other countries = 34 + 32 + 9 + 8 + 5 + 5 = 93
% of copper mined by the USA = 100 – 93 = 7%
4. What mass of copper is produced by Chile? Show how you worked it out.
Need to find 32% of 17 096 kt.
32/100 = 0.32 or
0.32 x 17 096 = 5470.72 kt
5. What is the meaning of the term “native” in the above text?
When a metal is chemically uncombined (not bonded) to another element.
6. Use the reactivity series and the information in the text to explain why is gold found in its native form in the Earth’s crust.
Gold is un-reactive – it is at the bottom of the reactivity series.
7. What is the name of the method used to extract aluminium from its ore?
Electrolysis
8. Name the type of chemical reaction that is used to extract iron from its ore?
Reduction reaction
Extraction of metals
Use the information on “extraction of metals” to help answer the following questions.
1. What is an “ore”?
______
______
2. Where are metal ores found?
______
______
3. What percentage of copper is mined by the USA? Show how you worked it out.
4. What mass of copper is produced by Chile? Show how you worked it out.
5. What is the meaning of the term “native” in the above text?
______
______
6. Use the reactivity series and the information in the text to explain why is gold found in its native form in the Earth’s crust.
______
______
7. What is the name of the method used to extract aluminium from its ore?
______
______
8. Name the type of chemical reaction that is used to extract iron from its ore?
______
______
Cost of Extraction
Metals like to exist as compounds – chemically bonded to other elements.
The more reactive a metal is the more likely it is to exist in its compound form and the harder it will be to extract. The more difficult the metal is to extract the more expensive it will be to extract!
More reactive = more difficult to extract = more expensive to extract!
Question
The cost of electricity for producing 1 tonne of aluminium from its ore is £2100. Recycling aluminium uses only 5% of the electricity needed to extract it. Calculate the cost of electricity needed to recycle 1 tonne of aluminium. [1]
Cost = £ ......
Cost of Extraction
Metals like to exist as compounds – chemically bonded to other elements.
The______reactive a metal is the more likely it is to exist in its compound form and the______it will be to extract. The more difficult the metal is to extract the more ______it will be to extract!
More reactive = more difficult to extract = more expensive to extract!
Question
The cost of electricity for producing 1 tonne of aluminium from its ore is £2100. Recycling aluminium uses only 5% of the electricity needed to extract it. Calculate the cost of electricity needed to recycle 1 tonne of aluminium. [1]
Cost = £ ......