An Experiment to Investigate How to Extract a Metal from its Ore
Pupil

Aim
(1) To examine how copper can be produced from a naturally occurring ore of copper called malachite or copper carbonate.
(1) To observe what happens when copper carbonate is heated strongly.
(2) To observe what happens when copper oxide reacts with sulphuric acid.
(3) To observe what happens when an iron nail is suspended in a solution of copper sulphate.

Apparatus/Materials
(1) Pestle & Mortar
(2) Tongs
(3) Boiling Tube (Pyrex)
(4) Beaker (100 cm3 )
(5) Dilute sulphuric acid solution 15 cm3
(6) Bunsen burner.
(7) Funnel, filter paper to fit and retort stand and clamp or tripod to fit.
(8) Clean iron nail.
(9) Malachite (Copper Carbonate) Approx. 5 g 

Diagram

(Stage 1)

Procedure (Stage 1)

(1) Crush the copper carbonate ore in a pestle and mortar unless it is supplied as a powder.
(2) Place about 2cm depth of the powder in a boiling tube.
(3) Heat it gently at first and then more strongly, until all the green copper carbonate has been converted to black copper oxide.
(4) Allow the boiling tube and its contents to cool for a few minutes.

Diagram (Stage 2)

Procedure (Stage 2)

(1) Add about 15 cm3 of dilute sulphuric acid to the cooled boiling tube. The tube will be about one third full.
(2) Gently heat for a few minutes. Hold the boiling tube at a slant and point the open end away from yourself and others. Do not let the liquid boil.

Diagram(Stage 3)

Procedure (Stage 3)

(1) Filter the mixture of blue solution and black solid. Discard the residue and filter paper in the bin.
(2) Place a clean iron nail in the blue solution in the beaker. After a few minutes lift the nail out of the solution using a tongs.
(3) Observe what the nail has been covered with. This is the copper metal which was originally in the malachite ore.

Conclusion

Stage 1
(1) State clearly what you see happening as you heat the ore.
(2) Write a word equation or a chemical equation to describe what is happening.

Stage 2
(1) State clearly what you see happening as the black powder is warmed in the sulphuric acid.
(2) Write a word equation or a chemical equation to describe what is happening.

Stage 3
(1) State clearly what you see happening as the iron nail sits in the blue solution.
(2) Write a word equation or a chemical equation to describe what is happening.

Questions related to the experiment
(1) When the copper carbonate ore is heated what substance other than copper oxide is produced?
(2) In stage 2 copper oxide reacts with an acid to form a salt and water. What type of compound does this make copper oxide?
(3) Why can iron displace copper from a solution of its salt?
(4) Some of the iron in the nail has reacted with the copper sulphate solution. What compound has it formed?

Teacher
Safety/Disposal
(1) The copper sulphate solution remaining is dilute and can be washed down the sink with plenty of water.
(2) Pupils must be instructed in how to heat a solution safely in a boiling tube. A boiling tube should never be more than one third full of liquid when being heated. It must be held at a slant to promote even heating by convection. It must always point away from people.

Experiment Notes
(1) Pupils need to be cautioned that the boiling tube will remain hot for a while after stage 1.
(2) In stage 2, repeated instruction on gentle heating will be required. A demonstration would be a good idea.
(3) The filter paper can be folded in four and opened with one layer on one side and three layers on the other to make a conical shape.
(4) Large iron nails are easier to grip with a tongs and have a greater surface area for reaction.
(5) Chemical equations are as follows:-

Stage 1         CuCO3 + Heat -----------------> CuO + CO2
Stage 2         CuO + H2SO4 ----warm---> CuSO4 + H2O
Stage 3         Fe(s) + CuSO4 (aq) -----------> FeSO4 (aq) + Cu(s)

Solutions to questions related to the experiment

(1) When the copper carbonate ore is heated what substance other than copper oxide is produced?
Carbon dioxide gas which escapes from the boiling tube. A similar decomposition of limestone (calcium carbonate) produces quicklime (CaO).
(2) In stage 2 copper oxide reacts with an acid to form a salt and water. What type of compound does this make copper oxide?
Copper oxide is a base but not an alkali as it is not soluble in water.
(3) Why can iron displace copper from a solution of its salt?
Iron is higher up in the activity series than copper and is therefore more reactive.
(4) Some of the iron in the nail has reacted with the copper sulphate solution. What compound has it formed?
It forms Iron Sulphate solution and given enough time the colour of the solution would change from a blue to a pale green as all the copper ions present were precipitated.

Related Course Topics
(1) Metals
(2) Electrochemistry
(3) Material Science Extension -- Ores