Question #a18c9

1 Answer
May 20, 2017

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".