* GCSE-science-CHEMISTRY 4. Extraction of copper & its purification by electrolysis at Doc Brown's Chemistry

DOC BROWN'S HOMEPAGE and WELCOME ALPHABETICAL SITE INDEX for chemistry KS3 SCIENCE QUIZZES and WORKSHEETS (~US grades 6-8) KS4 Science GCSE/IGCSE CHEMISTRY NOTES (~US grades 8-10) KS4 Science GCSE/IGCSE CHEMISTRY QUIZZES and WORKSHEETS (~US grades 8-10) KS4 Science GCSE/IGCSE CHEMISTRY SYLLABUS HELP LINKS (~US grades 8-10) ADVANCED LEVEL CHEMISTRY NOTES (~US grades 11-12) ADVANCED LEVEL CHEMISTRY QUIZZES and WORKSHEETS (~US grades 11-12) ADVANCED LEVEL CHEMISTRY SYLLABUS HELP LINKS (~US grades 11-12)  
DOC'S PICTURES - always travel with my camera!
extract1extract2 Doc Brown's Chemistry

 Mining of Minerals and Methods of Extracting of Metals 

4. The extraction of copper from copper ores and its purification by electrolysis

Scroll down for revision notes on extraction procedures and theory

Useful for school/college assignments/projects on ways of extracting metals from their ores

1. Introduction to Metal Extraction * 2. Extraction of Iron and Steel Making

3. Extraction of Aluminium and Sodium * 4. Extraction of copper and purification by electrolysis

5. Extraction of Zinc, Titanium and Chromium * 6. Economic & environmental Issues - metal extraction

GCSE Multiple choice Quizzes on metal extraction: Foundation (easier) or Higher (harder) and word-fill

Revision Notes KS4 Science IGCSE/O level/GCSE Chemistry Information Study Notes for revising for AQA GCSE Science, Edexcel 360Science/IGCSE Chemistry & OCR 21stC Science, OCR Gateway Science  (revise courses equal to US grades 9-10)

Other associated KS4 Science GCSE/IGCSE chemistry web pages on this site

 

memory help - element quizreactivity4a. The extraction of copper from copper ores and its purification by electrolysis
  • From copper carbonate ores* ...
    • The ore can be roasted to concentrate the copper as its oxide.
    • Water is driven off and the carbonate thermally decomposed.
    • copper(II) carbonate ==> copper oxide + carbon dioxide
    • CuCO3(s) ==> CuO(s) + CO2(g)
    • The oxide can be smelted by heating with carbon (coke, charcoal) to reduce the oxide to impure copper, though this method isn't really used much these days (the 'bronze age' method archaeologically!).
    • copper(II) oxide + carbon ==> copper + carbon dioxide
    • 2CuO(s) + C(s) ==> 2Cu(s) + CO2(g)
    • The carbon acts as the reducing agent - the 'oxygen remover'.
  • From copper sulphide ores ...
    • These include chalcocite/chalcosine = copper(I) sulphide Cu2S and covellite = copper(II) sulphide CuS
      • and chalcopyrite CuFeS2. which is one of the most important ores for the extraction of copper.
        • This can be roasted in air to produce copper(I) sulfide which is roasted again in a controlled amount of air so as not to form a copper oxide (see below).
        • 2CuFeS2 +  4O2 ==> Cu2S + 3SO2 + 2FeO
    • Copper sulphide ores can be rapidly roasted in heated air enriched with oxygen to form impure copper and this extraction process is called 'flash smelting'.
      • Nasty sulphur dioxide gas is formed, this must be collected to avoid pollution and can be used to make sulphuric acid to help the economy of the process.
      • copper(I) sulphide + oxygen ==> copper + sulphur dioxide
        • Cu2S(s) + O2(g) ==> 2Cu(s) + SO2(g)
      • or copper(II) sulphide + oxygen ==> copper + sulphur dioxide
        • CuS(s) + O2(g) ==> Cu(s) + SO2(g)
  • It is also possible to dissolve an oxide or carbonate ore in dilute sulphuric acid and extracting copper by ....
    • (1) using electrolysis see purification by electrolysis, or
    • (2) by adding a more reactive metal to displace it e.g. scrap iron or steel is used by adding it to the resulting copper(II) sulphate solution.
      • iron + copper(II) sulphate ==> iron(II) sulphate + copper
      • Fe(s) + CuSO4(aq) ==> FeSO4(aq) + Cu(s)

 top index

copper24b. The Purification of Copper by Electrolysis (extraction from ore above)

(c) doc b
  • The impure copper from a smelter is cast into a block to form the positive anode. The cathode is made of previously purified copper. These are dipped into an electrolyte of copper(II) sulphate solution. 
  • When the d.c electrical current is passed through the solution electrolysis takes place.  The copper anode dissolves forming blue copper(II) ions Cu2+.
  • These positive ions are attracted to the negative cathode and become copper atoms. The mass of copper dissolving at the anode exactly equals the mass of copper deposited on the cathode. The concentration of the copper(II) sulphate remains constant.
  • Any impurities present in the impure copper anode fall to the bottom of the electrolysis cell tank. This 'anode sludge' is not completely mineral waste, it can contain valuable metals such as silver!
  • See section above for extraction of impure copper from an ore.

Raw materials for the electrolysis process:

  • Impure copper from a copper smelter.

  • Electrolyte of aqueous copper(II) sulphate.

  • A pure copper cathode.

Electrolysis is using d.c. electrical energy to bring about chemical changes at the electrolyte connections called the anode and cathode  electrodes.

An electrolyte is a conducting melt or solution of ions which carry the electric charge as part of the circuit.

Scrap copper can be recycled and purified this way too ,and is cheaper than starting from copper ore AND saves valuable mineral resources.

 The redox details of the electrode processes:
  • At the positive (+) anode, the process is an oxidation, electron loss, as the copper atoms dissolve to form copper(II) ions.

Cu(s) ==> Cu2+(aq) + 2e-

  • at the negative (-) cathode, the process is a reduction, electron gain by the attracted copper(II) ions to form neutral copper atoms.

Cu2+(aq) + 2e- ==> Cu(s)

  • Note: Reduction and Oxidation always go together, hence the use of the term redox change or reaction.
  • Electroplating is mentioned on the ...

top sub-indexCopyright Dr W P Brown 2000-2010 All rights reserved on the revision notes pages, quizzes, worksheets, x-words etc.
DOC'S PICTURES - always travel with my camera! images and notes