A mixture of magnesium carbonate and magnesium oxide of mass #12.46g# underwent fierce heating. After heating, there were #8.43g# of salt remaining. What were the masses of magnesium carbonate, and magnesium oxide in the original sample?

Question

9124 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-05-19T05:30:47

Well, we use the general decomposition #("calcining")# reaction of metal carbonates.............

#MgCO_3(s)+DeltararrMgO(s) + CO_2(g)#

And we would have to heat the magnesium salt VERY fiercely to get complete decarboxylation.

#"Moles of carbon dioxide LOST"# #=# #(4.40*g)/(44.01*g*mol^-1)#

#=0.010*mol#

And therefore in the original mixture there were #0.010*mol# #MgCO_3#, i.e. a mass of #0.010*molxx84.31*g=8.43*g#.

The balance of the salt must have #MgO#, which is (reasonably) inert to heating.

#"Mass of MgO"# #=# #12.46*g-8.43*g=4.03*g#.

A mixture of magnesium carbonate and magnesium oxide of mass #12.46*g# underwent fierce heating. After heating, there were #8.43*g# of salt remaining. What were the masses of magnesium carbonate, and magnesium oxide in the original sample?