F3 Chem

Heat the rocks containingcalcium carbonate to obtain calcium oxide.
calcium carbonate → calcium oxide + carbon dioxide
CaCO3­ → CaO + CO2

Then electrolyse the molten liquid of calcium oxide to obtain calcium at thecathode.
calcium oxide → calcium + oxygen
2CaO → 2Ca + O2

2011-06-16 18:59:45 補充：
There is no molten liquid of calcium carbonate, because it is decomposed on heating before melting.

2011-06-17 01:51:03 補充：
mauricesum gave an incorrect answer.

Calcium oxide does not react with aluminium, because calcium is more reactive than aluminium.

2011-06-17 01:53:42 補充：
己式庚辛所提供的方法是正確的，但對中三同學來說可能會間接一點。

CaO + Al → Al2O3 + Ca is it reacted?
Calcium is more reactive than aluminium.Is it right.
Also I had saw a book.Mg +NaOH-> Na+MgOH.Is it right?or I am wrong?

002 answer suggested that aluminium displaces calcium from calcium oxide. It is IMPOSSIBLE.

Aluminium is less reactive than calcium. A less reactive metal can NEVER displace a more reactive metal.

Heat the rocks containing calcium carbonate
This process will release carbon dioxide and leave only calcium oxide
Heat the calcium oxide with aluminium
(this reaction is known as themite reacion)
This process will produce aluminium oxide and calcium metal

2011-06-16 22:42:33 補充：
Equations:
CaCO3 → CaO + CO2
CaO + Al → Al2O3 + Ca

melting point of calcium oxide is probably too high (>2500 degree), difficult to obtain the molten form.

instead, add excess hydrochloric acid, turn it into CaCl2; evaporate to dryness, heat to melt (<800 degree), electrolyze to obtain calcium metal.

electrolysis of its molten ore (calcium carbonate)