# How does magnesium carbonate decompose under heating?

$M g C {O}_{3} \left(s\right) + \Delta \rightarrow M g O \left(s\right) + C {O}_{2} \left(g\right) \uparrow$
Most metal carbonates decompose according to this scheme to give the metal oxide and carbon dioxide gas. I leave it to you to calculate the percentage loss with respect to the magnesium salt. The oxidation numbers are constant for products and reactants: Mg(+II); C(+IV); O(-II) for products and reactants; i.e. this is not a redox reaction.