Question #a18c9

1 Answer
May 20, 2017

Answer:

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"#.