Burning Calcium Carbonate
Name: Joe V.
A text book question says CaCO3 burns with O2 to form CaO
and CO2.... does it really burn, or just decompose with heat. If it
burns, what is the balanced equation?
I think you are right in suspecting that CaCO3 does not undergo combustion, I
do not even think that it undergoes decomposition under most laboratory
conditions. I know that in my labs, we use a mixture of MgCO3 and CaCO3 (to
simulate dolomite) and count on the fact that we can decompose MgCO3 with a
bunsen burner, but the CaCO3 remains intact.
Greg (Roberto Gregorius)
CaCO3 does not combust, by the definition of the word. It is "converted"
into lime (CaO) by a thermal decomposition reaction. This IS a reversible
reaction. When the calcium carbonate is heated to around 932 F, it will
liberate a CO2 molecule and will become CaO. This, demonstrated as a one
way reaction is shown as;
CaCO3 + HEAT (932 F) == CaO (lime) + CO2.
I do not know the exact mechanism of this decomposition. Nor do I know how,
exactly, the CO2 would combine with lime (CaO) to go back to its original
CaCO3. But I have read that it is a reversible reaction.
Thanks for the question.
Joe- you seem to have the correct understanding. It just decomposes with
CaCO3 <--> CaO + CO2.
In either state, both carbon and calcium are fully oxidized, cannot hold
any more oxygen atoms.
I believe that CaCO3 decomposes when heated to form CaO and CO2 without the
need of any additional O2. This is not combustion in the usual sense of
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Update: June 2012