Group 2: Alkaline earth metals
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Can you explain why magnesium carbonate is broken down to magnesium oxide and carbon dioxide when it undergoes thermal decomposition? I want to know what does the heat actually do to magnesium carbonate molecules
Note that magnesium carbonate consists of magnesium ions and carbonate ions. There are no molecules in the solid.
The exact mechanism is probably not known. What has to happen is that the carbonate ion breaks down into carbon dioxide and an oxide ion.
Since the oxide ion is smaller than the carbonate ion (but has the same 2- charge) this means that energy is given out as the lattice contracts as the carbonate turns into the oxide.
Energy is needed to break bonds between carbon and oxygen atoms in the carbonate ions.
Energy is also needed to get the reaction going - by starting bond breaking (activation energy).
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updated: 18 January 2006
