Question

Question #a18c9

Answer 1

The mass loss must represent `CO_2`; and thus we get `8.43*g` magnesium carbonate, and `6.03*g` `MgO`.

Explanation:

The mass loss must represent `CO_2`. Why? Because carbonates are KNOWN to undergo thermal decomposition according to the following rxn:

`MgCO_3(s) + Delta rarr MgO(s) + CO_2(g)uarr`

And so ..........................

`"moles of carbon dioxide "-=" moles of magnesium carbonate"`

`"Moles of carbon dioxide"=(4.4*g)/(44.01*g*mol^-1)=0.0100*mol`,

which constitutes a mass of `0.0100*molxx84.31*g=8.43*g` WITH RESPECT TO `"magnesium carbonate".`

The balance, `(12.46-8.43)*g=6.03*g` WITH RESPECT TO `"magnesium oxide"`.