The Extraction Of Metals Notes
This is a sample of our (approximately) 3 page long The Extraction Of Metals notes, which we sell as part of the Chemistry AS Notes collection, a A package written at Manchester High School For Girls Sixth Form in 2013 that contains (approximately) 54 pages of notes across 17 different documents.
The Extraction Of Metals Revision
The following is a plain text extract of the PDF sample above, taken from our Chemistry AS Notes. This text version has had its formatting removed so pay attention to its contents alone rather than its presentation. The version you download will have its original formatting intact and so will be much prettier to look at.
Unit 2: 13 The Extraction of Metals
THE EXTRACTION OF METALS The occurrence of metals in the Earth's crust:
• Metals are found in the Earth's crust, the least reactive as their elements and the more reactive as metals oxides and sulﬁdes.
• Rocks that contain a high enough percentage of metal to be extracted commercially are ores.
• Aluminium and iron are the most abundant metals in the Earth crust.
METHODS OF EXTRACTION
Most compounds are found as OXIDES OR SULFIDES. Sulﬁdes are converted to oxides by ROASTING IN AIR
e.g. zinc sulﬁde + oxygen → zinc oxide + sulfur dioxide
2ZnS(s) + 3O2(g) → 2ZnO(s) + 2SO2(g) Roasting sulﬁde ores produces sulfur dioxide which leads to acid rain, however this can be collected and used to manufacture sulfuric acid.
The extraction of metals involves reduction. In these reactions, the metal ions gain electrons:
• Using hydrogen as the reducing agent (for tungsten)
• Electrolysis (aluminium from puriﬁed bauxite)
• Using a more reactive metal (titanium from TiO2 via TiCl4)
• Using carbon and carbon monoxide as the reducing agents (for extracting, iron, copper and manganese) Which method is used depends on;
1. the energy requirements - extraction uses large amounts of energy
2. the cost of the reducing agent - carbon (in the form of coke) is cheap and widely used but more reactive metals are more expensive
3. the metal purity required - the higher the required purity, the greater its cost.
Recycling metals: Recycling metals;
> saves resources (e.g. metal ores)
> creates less waster (e.g. mining waste)
> saves energy resources (less energy needed to recycle than to extract from ores)
> reduces air pollution (e.g. CO2 and SO2 and CO) However there are costs associated with sorting and transporting metals to be recycled. RECYCLE COPPER by reacting scrap copper with sulphuric acid or a speciﬁc enzyme to form solutions containing Cu2+(aq).
-The copper can be extracted by reaction with scrap iron. Cu2+(aq) + Fe(s) → Cu(s) + Fe2+(aq)
CHEMISTRY AS NOTES
****************************End Of Sample*****************************
Buy the full version of these notes or essay plans and more in our Chemistry AS Notes.